BRACHYPODELLA,, JAMAICAN. 9? 



tered within, the lip reflexed. Axis straight, thick and vari- 

 ously sculptured in the lower half of its length. Apical whorl 

 high. Type B. alba C. B. Ad. 



The radula is very long and narrow, its sack projecting free 

 into the cavity of the body (pi. 14, fig. 2, B. agnesiana). The 

 teeth (pi. 10, fig. 21, B. alba occidentalis, Great Valley estate, 

 and fig. 22, B. agnesiana, Creighton Hall) resemble those of 

 Apoma. The centrals have a very wide cusp, as in Bmchy- 

 podella s. sir. The inner lateral has no trace of an ectocone 

 (fig. 23). The outer lateral has a boss without overhanging 

 cusp in place of the ectocone. The marginals have bilobed 

 cusps. Other characters as in the genus generally. 



B. agnesiana is said by Gloyne to be viviparous. 



The axis in shells of this group is thickened in the lower 

 half, and more or less distinctly biplicate, somewhat as in the 

 Haitian Strophina. In the upper half it retains the earlier 

 structure, is thin and singly plicate, the spiral being contin- 

 uous with the lower of the two cords in the thickened portion. 

 This spiral is often serrate or spinose; and the whole surface 

 of the pillar may be roughened or granulate, but this minor 

 sculpture varies individually within wide limits. In B. dimi- 

 nuta there has been extraordinary hypertrophy of the asperi- 

 ties of the spiral cords, which become few in number and en- 

 larged into thick hooks, which stand obliquely opposite on the 

 two cords, in pairs, almost exactly reproducing the structure 

 of the pillar in the Cuban Urocoptis (Idiostemma) uncata 

 (Cf. pi. 2, f. 19, with Vol. XV, pi. 44, f. 33). It will be noted 

 that in U. uncata also, the hooks have arisen from primitive 

 small nodes on a biplicate axis, as shown by the related, less 

 evolved, species. 



Another extraordinary feature of Mychostoma is the pres- 

 ence in at least one species of a structure resembling the clau- 

 silium of the genus Clausilia. In B. alba occidentalis there is 

 found within the fifth whorl from the base a tongue-shaped, 

 whitish process (pi. 1, figs. 14, 15), which above, at its origin, 

 is continuous with the solid axis, but below hangs free in the 

 cavity. When wet, this process is flexible; and is found to 

 consist of a thin plate of conchiolin covered with an uncon- 



