hardened and frequently more or less united at the base, the inner ones often broad and scale-like. In some specimens, however, of C. calyculatus, Cav., and its allies the hardening appears so slight as to bring the genus into very close connexion with Pennisetum.

13. PENNISETUM, Pers., the principal genus of the group, would now contain about forty species, chiefly African, amongst which two or three extend to the Mediterranean region, tropical or central Asia, or tropical America, and a very few may be endemic in Asia, Australia, or America. It has been at various times proposed to separate several genera from it, and two or three of these have been pretty generally adopted; but they pass so gradually one into the other, and their chief characters, derived from the hairiness or numbers of the involucral bristles, are so little in accord with any other characters or habit, that the several following groups can scarcely be considered even as definite sections. Pennisetum itself has been restricted to those species in which the bristles are numerous and some or all of them more or less hairy; whilst those in which the whole of the bristles are perfectly glabrous form the genus Gymnotrix, Beauv. But however easy this distinction may appear at first sight, it is neither natural nor always definite. In a few African species proposed by Figari and De Notaris as their genus Eriochate, the whole of the setæ are densely woolly-plumose; in some of the commoner species numerous outer setæ of each involucre are glabrous, and as many or more or fewer of the inner ones are hairy. In P. flaccidum, Munro, from East India, and P. Benthamianum, Steud., from tropical Africa, amongst very numerous glabrous ones there are generally only two or three hairy ones, or sometimes none at all, thus forming a gradual connexion with the true species of Gymnotrix, where the setæ are always quite glabrous; and there is nothing else whatever to distinguish the two series even as marked sections. P. lanatum, Klotzsch, is a remarkable Himalayan species, in which the involucral bristles are few, sometimes reduced to a single long rigid branched one, either plumose or glabrous, showing well the true nature of the involucre of the genus. Penicillaria, Willd., often still retained as a genus, was founded upon a plant frequently cultivated in the Indo-African regions, which may at first sight appear to be abundantly distinct. The long dense cylindrical spike or spike-like panicle is often above a foot long and an inch in diameter, although in other cultivated specimens not above

half that size. The involucres sometimes remain persistent after the spikelets have fallen away, and the filiform styles are remarkably long; but many cultivated specimens and some East-African ones, possibly wild, offer so much variety in these respects, some passing quite into normal Penniseta, that it seems probable that the peculiarities of habit have arisen from long cultivation. The long styles united at the base occur in other species, amongst which P. (Gymnotrix) macrostachyum, Brongn., has on that account been proposed by Hasskarl as a genus, under the name of Sericura. Amphochata of Andersson is a Galapagos species of the Gymnotrix group, with small spikelets in slender pedunculate spikes, forming a loosely paniculate inflorescence, very different from that which characterizes the greater number of Penniseta, but closely connected with them through the several varieties of P. (Gymnotrix) tristachyum, Kunth. In P. (Gymnotrix) unisetum, Nees, an African species proposed as a genus by Figari and De Notaris under the name of Beckeropsis, this peculiar inflorescence is carried still further, and the involucre is sometimes reduced to a single bristle (always above the articulation and falling away with the spikelet), though I usually find 2, 3, or even more bristles. It is probable that the plant figured by Beauvois as Setaria longiseta is this same species of Pennisetum. Steudel's proposed genera Catatherophora and Oxyanthe are normal species of Pennisetum (Gymnotrix).

14. PLAGIOSETUM, Benth., is a single Australian species, which I characterized as a genus chiefly from its peculiar inflorescence and habit, which prevented my retaining it in Pennisetum without an extension of the generic character beyond what I felt justified in proposing.

15. PARATHERIA, Griseb., is a single West-Indian species, which proves to be identical with the Brazilian plant since published by Doell as a section of Leptachyrium of Panicum, but which is evidently more nearly related to Pennisetum. The inflorescence is a simple spike-like panicle, of which the numerous short articulate branchlets or pedicels are continued beyond the single spikelets into long awns or bristles, which fall away with the spikelet like the involucres of Pennisetum, thus forming in some sort a connexion between the Cenchrus group of genera and the following one.

Our third or Chamæraphis group of Paniceæ consists of seven small genera, loosely connected by a character which may be con

sidered as rather artificial than natural, but which I believe to be constant. The spikelets are nearly those of Panicum, but with the fruiting glume usually less hardened; the inflorescence is nearly that of the paspaloid Panica or of the Chlorideæ, but distinguished from the former by the rhachis of the partial spikes or fascicles or branches of the panicle being produced beyond the spikelets into a more or less rigid point. From Chloride the articulation of the pedicel below the spikelet always separates the present group. The genera are:-16. ECHINOLENA, Desv., a single tropical American species (E. scabra), which has quite the rigid single spike of some Chlorideæ, but the spikelets of Paniceæ intermixed with barren ones, on which account Rudge originally figured the plant as a Cenchrus. The loosely paniculate species added to Echinolana by Kunth have been rightly restored to Panicum by Trinius. 17. CHAMÆRAPHIS, Br., four Australian or tropical Asiatic species, fully described in my 'Flora Australiensis.' 18. SPARTINA, Schreb. (Trachynotia, Mich., Limnetis, Pers., Ponceletia, Thou., Solenachne, Steud.), five or six European, African, or American species, chiefly maritime, has been usually placed amongst Chlorides; but the spikelets themselves containing a single terminal flower, and the articulation of their pedicels, are quite those of Paniceæ, not of Chlorideæ. 19. XEROCHLOA, Br., three Australian species, 20. STENOTAPHRUM, Trin. (Diastemanthe, Steud.), two or three tropical maritime species, 21. PHYLLORHACHIS, Trimen, a single one from Angola, and 22. THUAREA, Pers. (Ornithocephalochloa, Kurz), also a single maritime species from the shores of the Indian and South-Pacific oceans, are all perfectly isolated genera whose peculiarities have been well pointed out. Stenotaphrum is the only genus I know in the tribe Paniceæ which has the rhachis of the inflorescence articulate; but this can usually not be perceived except in an advanced state, and has been denied by some botanists. I have already alluded (Journ. Linn. Soc., Bot. xvii. 196) to Kunth's mistake, which induced him to alter Persoon's name Thuarea (abridged from Thouars's then MS. name of Microthuarea) to Thouarea.

There remain seven very anomalous genera, but little connected with each other, and still less with any other genera of Gramineæ, but which have all more of the general character of Paniceæ than of any other tribe. They have all been well defined and illustrated, and require no more than a bare enumeration on the present occasion. They are:-23. SPINIFEX, Linn., three Austra

lian species, of which one extends to New Zealand and New Caledonia, with a fourth from the coasts of tropical Asia closely allied to one of the Australian ones; 24. OLYRA, Linn., about twenty species, of which one is tropical African, the remainder tropical American, including as a section Lithachne, Beauv. (Strephium, Schrad., Raddia, Bertol.); 25. PHARUS, Linn., five American species; 26. LEPTASPIS, Br., three or four tropical species from Africa, Asia, or Australia, a genus nearly allied to, but perfectly distinct from, Pharus; 27. LYGEUM, Linn., a single maritime species from the Mediterranean region; 28. STREPTOCHETA, Schrad. (Lepideilema, Trin.), and 29. ANOмOCHLOA, Brongn., both single Brazilian species.

Tribe II. MAYDEÆ.

The grasses composing this tribe are usually erect and tall, with flat, long or broad leaves, the spikelets always unisexual, the males, in all except Pariana, in the upper part of the plant or of the inflorescences, the females at the base or in the lower axils, the grain, in all except Zea, enclosed in a hard stony case, formed variously of an outer glume or of a subtending bract. Where there are several fruiting spikelets in one inflorescence they are superposed, and each one falls away separately with the internode to which it is attached, the rhachis of the spike disarticulating at each node. The male spikelets either wither away or remain persistent above at the end of the stem or on the top of the uppermost fruiting spikelet. The tribe is thus perfectly well defined and quite distinct from any other; and the eight following genera of which it is composed, all tropical or American, and mostly small or monotypic, are likewise marked by positive cha

racters.

1. PARIANA, Aubl., an American genus of about ten species, is in many respects anomalous. The females, as in the other genera, are single at each node of the articulate inflorescence; but the male spikelets, instead of forming a terminal panicle, surround the female at each node and fall away with it. The stamens are also indefinite in number, ten to twenty in the spikelets examined, but Nees found as many as forty; whilst in all the other genera of the tribe there are only the normal three. Doell describes the female flower as having five lodicules; but here there is probably a mistake. I have never been able to see more than three, which are rather large; but there are

sometimes within them two or three very minute scales, which may possibly be rudimentary staminodia. Doell has also proposed to separate generically, under the name of Eremites, a Brazilian plant which, from the single spike I have seen as well as from his description and figure, appears to be no more than

a starved state of some true Pariana.

2. Coix, Linn. (Lithagrostis, Gærtn.), contains three or four East-Indian species closely allied to each other, one of which, the common "Job's tears," is widely spread over the warmer regions both of the New and the Old World, but in many places of comparatively modern introduction. The hard covering of the fruit here consists of the sheath of a subtending bract, the withered glumes as well as the internode of the rhachis remaining entirely enclosed within it.

3. POLYTOCA, Br. (Cyathorhachis, Nees), three or four tropical Asiatic species in which the stony case of the fruit is formed by the outer empty glume, which is completely closed over the remainder of the spikelet as well as the internode to which it is attached. The species are:-(1) P. bracteata, Br. (Coix heteroclita, Roxb.), spicis masculis terminalibus ramosis, inferioribus androgynis v. fœmineis plerisque simplicibus, glumis exaristatis: (2) P. Wallichiana (Cyathorhachis Wallichiana, Nees), spicis masculis terminalibus ramosis, inferioribus androgynis v. fœmineis plerisque simplicibus, spicularum mascularum gluma exteriore longe tenuiterque aristata: (3) P. macrophylla, sp. n., spicis longis (omnibus ?) androgynis simplicibus, glumis acuminatis exaristatis; folia adsunt 2-pedalia, 2 poll. lata, spicæ 4-6-pollicares from the Louisiade Archipelago (Mac Gillivray).

4. CHIONACHNE, Br., contains three species from tropical Asia or Australia, in which the hardened fruit-case is formed, as in Polytoca, of the outer empty glume, but the internode of the rhachis, instead of being completely enclosed within it, is embraced only by its thickened margins, and is seen lying as it were in a groove of the fruit-case.

5. SCLERACHNE, Br., is a single Javan species, with the fruit nearly of Chionachne, but with a different habit, and the hardened outer glume is produced beyond the fruit into an open membranous appendage.

6. TRIPSACUM, Linn., consists of two or three American species with the terminal male inflorescence usually more branched than in the preceding Asiatic genera, approaching that of Euchlæna