50 BRACHYPODELLA, S.-G. AMPHICOSMIA. 



The species are illustrated on plate 3. The group was sup- 

 posed to be subordinate to Urocoptis until I investigated the 

 radula of B. truncatula, when it became at once evident that 

 Amphicosmia is a specialized Brachypodella. The general dis- 

 position of the teeth (pi. 9, figs. 6, 7, 8) is as in other subgenera 

 of that genus. The central tooth (fig. 8, profile) is much 

 narrower than in the typical section of Brachypodella (see 

 figs. 3, 5, 14-16) , though slightly bilobed at the cutting edge ; 

 and the inner lateral has the basal-plate much wider, not con- 

 tracted into a long neck. In these respects the teeth of Am- 

 phicosmia approach those of Strophina (pi. 10, f. 19), Brevi- 

 pedella (pi. 9, f. 1, 2) and the Cuban group Gyraxis. The 

 eetocone of the inner lateral (see pi. 9, fig. 6) is a good deal 

 reduced, however, not forming an overhanging cusp, as in 

 Strophina. The marginal teeth are comparatively well de- 

 veloped, as in Strophina. While rather isolated, it seems that 

 Amphicosmia is more closely related to Strophina than to 

 other known groups of Brachypodella. 



Key to Species of Amphicosmia. 



I. Somewhat glossy, closely and finely striate species. S. 

 Domingo. 



1. Rather large, diam. 4-5 mm., the neck short, axial 



lamellae finely crenulate, smooth in the lower 

 whorls. B. salleana, no. 6. 



2. Smaller and slender, diam. 2.3-3.3 mm., the neck 



long, axial lamellae serrate. 



B. hjalmarsoni, no. 7. 



II. Dull, rib-striate, the intervals much wider than the rib- 

 lets. Haiti. 



1. Neck short, conspicuously swollen at the periph- 



ery, the keel near the middle of its base; axial 

 lamellae finely and very weakly crenulate. 



B. truncatula, no. 8; B. cristata, no. 9. 



2. Neck longer; last whorl flattened on periphery 



and base, the keel latero-basal ; axial lamellae 

 denticulate. B. dohrni, no. 10. 



