Mr. J. Miers on the genus Thinogeton. 357 



tcrs of the spicula however are not given, and without a know- 

 ledge of these, no very conclusive opinion ought to be foniied 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 two 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 John Mters, Esq., F.R.S., F.L.S. 



[Continued from p. 25G ] 



Thinogeton. 



This 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- 

 calyXy proposed by Dr. Hooker for a plant obtained by IMr. 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 w^oody ; the petiole 

 is rounder, thicker, and grows to 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 



