BRACHYPODELLA. 43 



I have been able to dissect only the most highly evolved forms, 

 of Brachypodella. 



There is no character of the shell common to all the forms 

 of Brachypodella, which will separate the genus from all 

 forms of Urocoptis; though the various minor groups when 

 once learned are more or less characteristic. The chief differ- 

 entiation of the two groups has been in the structure of the 

 radula. 



Brachypodella is very closely related to Pineria, or at least 

 to P. viequensis, which has a radula of the same type. In P. 

 viequensis, however, the ectocones of both lateral teeth are 

 larger and better developed than in Brachypodella. Brachy- 

 podella differs widely from Pineria in having the columellar 

 margin of the peristome built forward, while in Pineria it is 

 not built forward from the columella proper, being formed 

 as in Liguus, Oxystyla, etc. 



While Brachypodella contains fewer species than Urocoptis, 

 there has been fully as much differentiation within the genus, 

 and when the soft parts are studied it may be found neces- 

 sary to divide it into several genera, which, however, will in 

 any case be more nearly allied to one another than to Uro- 

 coptis, etc. At present the phylogenetic arrangement of the 

 several series of species is based upon the structure of the 

 axis, of the apical whorls, and of the radula. The typical 

 section of the genus contains apparently the least special- 

 ized existing forms. 



Key by shell-characters to subgenera of Brachypodella. 



I. Axis encircled by two strong, thin, subequal lamellae, 

 serrate or crenulate at the edges; base carinate. 

 Island of Santo Domingo. 



Subgenus AMPHICOSMIA, sp. 6 to 10. 

 II. Axis thickened in the lower half of the shell, cylindric, 



biplicate or nodose ; base carinate. 

 1. Shell stout, barrel-shaped or cylindric, ribbed; axis 

 thick, with two smooth, low spiral cords. Santo 

 Domingo. STROPHINA, sp. no. 11. 



