176 Mr. J. Miers on some genera of the Icacinaceae. or papillary tubes, here sloping outwards on each side the cord ; c, truncated vessels of the marginal plexus ; d, d, small channels of intercameral communication ; e, grand semilunar or crescentic channel of ditto ; /, septum. Fig. /• Diagram of vertical section to show the situation of the interseptal vessels : a, a, interseptal vessels ; h, septum ; c, grand channel of intercameral communication ; c?, part of spicular cord. Fig. 8. Enlarged view of first-formed chambers of Operculina Arabica : a, central cell or chamber ; b, b, b, probable forms of last cham-bers in process of development. Fig. 9. Diagram of vertical section of Nummulites acuta, Sow. : a, spicular cord ? ; b, truncated vessels of marginal plexus ; c, c, chambers of central plane; d, d, vertical interseptal vessels (the "perforations," &c. of Dr. Carpenter) ; e, e, horizontal interseptal vessels ; /, /, /, chambers on each side the central plane ; g, g, g, vertical tubes. XVI. — On some genera of the Icacinacese. By John Miers_, Esq., F.R.S., F.L.S. [Continued from p. 119.] Emmotum. This neglected genus was proposed by Desvaux in 1825 upon a plant from Guiana. By Endlicher it was referred to Leretia of the ' Flora Fluminensis/ with which it neither accords in the appearance of the leaf nor the mode of its inflorescence : Hamil-ton's character as given in his ' Prodromus/ notwithstanding its brevity, is sufficiently well marked to show that it does not differ from Poffopetalum, founded by Mr. Bentham in 1840 ; indeed the Emmotum fagifolium J Desv., corresponds with Pogopetalum acu-tuMj Benth., both from Guiana, so as to leave no doubt of their identity : according therefore to the austere rule of science, the latter name must give way to the former. Mr. Bentham in establishing his genus recorded two species, and has since de-scribed two others, and I have now to add a fifth. All the spe-cies, which are from Guiana and intertropical Brazil, seem to form good-sized trees, with very thick coriaceous leaves of a peculiar appearance ; their inflorescence is in axillary crowded fascicles of rather small flowers, which are distinguished by having petals densely beset on their inner face with long red silky hairs arising from an elevated costal nervure. Their chief peculiarity, however, consists in the unusual structure and sin-gular mode of dehiscence of their anthers, which are formed of two opposite, unilocular, valveless, and separate cells, the pollen being discharged extrorsely through a fissure arising from the secession of the dorsal margin of each boat-shaped cell from the very fleshy connective, features that have hitherto escaped obser-
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