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 302 OBSERVATIONS ON PLANTS

this calcar is equally manifest in the terminal rudiment of the locusta. The present, therefore, is a case of more re- markably oblique articulation in grasses than even that 245] existing in Ilolcus acicidaris (Andropogon acicularis, Betz), which led to the formation of CenirojjJiorum, a genus still admitted by Professor Sprengel,^ and respecting the structure of which a very singular explanation has been lately offered by M. Raspail.^ In one respect, the two cases differ. In Banthonia [Centrojjodia) Forshalii, the articulations being in the axis of the locusta or spicula, each flower appears to have this spur-like process ; while in Holcas CRhapJds) acicularis, the joint being in the peduncle or branch of the racemus, the spur is common to three locustae.

Dr. Fischer, in whose herbarium the specimen was ob- served which led to the formation of Centrophorum, will probably recollect the communication made to him on the subject of that plant, of which Dr. Trinius himself has since corrected the characters. He retains it, how- ever, as a distinct genus, for v\diich he has adopted the name Rhaphis, given to it by Loureiro, by whom it Avas originally proposed on other; but not more satisfactory grounds.

Triraphis Pumilio is the second plant of this family to be noticed. It is undescribed, and belongs to a genus of which the only two published species Avere found in the intratropical part of New Holland.^ In several points of structure the African plant is very different from T.^jun^ens, the first of these species ; in some respects it approaches to mollis, the second species, especially in the inequality of its setae or aristcC ; but it differs from both in habit, and in having only one perfect flower in each locusta.*

Of Pennisetum dichotomum {Delile, Flore cVUf/yjjfe, p. 15, tab. 8,/. 1), which, in several different states, is in the collection, it is remarked by Dr. Oudney that " it

1 Si/st. Veg. 1,;;. 132. 2 Annul, des Scien. Kat. 4, p. 425.

3 Proclr. Flo,\ Nov. Boll 1, ;;. 185. ^

^ Triraphis Pumilio, panicula coavctata abbreviata, locusta glumam vix supe- raiite 3-1-liora : flosculo infimo licrraaplirodito ; rcliquis neutris uuivalvibus.

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