~ 
Mr. J. Miers on the genus Thinogcton. 357 
ters of the spicula however are not given, and without a know- 
ledge of these, no very conclusive opinion ought to be formed on 
the subject. In the abstract of Nardo’s report, we casually learn, 
undoubtedly, that the spicula are “ sharp at one end and rounded 
at the other” in V. Michelini; but in the C. spinosa, which 
Mr. Morris considers identical with it, they are of ¢wo kinds; 
one fusiform and bent in the centre, the other with a globular 
enlargement at one end. It would therefore seem probable that 
these two species at least are distinct. The fact of specimens 
occurring in the same species of shell is not of much value in 
determining their identity: I have already described six or seven 
species procured from the same matrix. 
I remain, dear Sir, yours truly, 
ALBANY Hancock. 
XXXIX.—Contributions to the Botany of South America. 
By Joun Mtzgrs, Esq., F.R.S., F.L.S. 
[Continued from p. 256. ] 
THINOGETON. 
Tus interesting genus was founded by Mr. Bentham upon one 
of the plants collected on the coast of the Pacific, near Guayaquil, 
during the voyage of the ‘Sulphur ;’ it is identical with Dictyo- 
calyx, proposed by Dr. Hooker for a plant obtained by Mr. Dar- 
win in one of the islands of the Gallapagos group. In many 
respects its characters approach so closely upon Cacabus, that 
some might feel disposed to consider them as congeneric; its 
habit, however, is not so herbaceous, its stems are more strag- 
gling, terete, and though fistulose, are more woody ; the petiole 
is rounder, thicker, and grows te an unusual length (three or 
four times that of the blade) after the full growth of the leaf ; 
the corolla is less campanular, more infundibuliform, and after 
the impregnation of the ovarium, coils up spirally as in Convol- 
vulus, and remains attached to the calyx until the fruit is ma- 
tured; the stamens are more unequal and shorter, the filaments 
less slender and more arched at their origin than in Cacabus ; the 
epigynous gland crowning the ovarium is much larger, more than 
hemispherical, being gradually lost in the texture of the more 
slender basal portion, while in Cacabus it is distinct, prominent, 
and much smaller, rising on the summit of the germen, like a 
small bulbular expansion of the style. A still more marked dif- 
ference is seen in the calyx, which in the florescent state in Thi- 
nogeton, is of much smaller diameter, quite tubular and invests 
the contracted base of the corolla; it is of thicker texture, and 
