﻿DALL] SHELLS COLLECTED IX THE BAHAMAS 44 1 



last whorl usually ribbed, those preceding irregularly striate or 

 smooth; it has one more whorl, the parietal callus is not only con- 

 tinuous but usually thick when fully adult ; the parietal lamina rela- 

 tively sharp and clean cut, the axial one invisible from in front; 

 the umbilicus open instead of closed. The two forms referred to 

 variabile as varieties are similarly colored and from the same locality, 

 but represented by only three specimens. Notwithstanding the 

 enormous difference in size it seems more prudent for the present 

 to regard them as forms of one species. 

 Cerion {Strophiops) britnneum new species. PI. i.vm, fig. 9. 



Shell of moderate size, solid, strong, opaque, while, richly striped 

 and flecked axially with dark chestnut brown; form subcylindric 

 with a rather pointed apex and slightly attenuated last whorl. Nu- 

 clear whorls two and a half, pale brown, partly transversely striate; 

 subsequent whorls about eight, obsoletely ribbed, the ribbing strong- 

 est on the base ; umbilicus closed ; peristome broad, thick, simple, 

 strongly reflected, yellowish white : the parietal part thin, interrupted 

 except in fully adult specimens. The throat is livid brown, the 

 parietal lamina low, about one third of the last whorl in length, the 

 axial lamina feeble. 



Height of 

 Shell. 



28.5 



26.0 



This appears to belong the eximium group, but differs from that 

 species by its nearly obsolete ribbing, base not paler than above, the 

 dark brown throat, the thin and usually incomplete parietal callus, 

 and the parietal lamina not prolonged into the older half of the last 

 whorl. 



The specimens were obtained at Governor's Harbor, Eleuthera. by 

 Messrs. Bean and Riley in 1903. U. S. Nat. Mus., No. 173.266. 

 Cerion (Strophiops) plegmatunt new species. PL lviii, fig. 5. 



Shell of moderate size, light and thin, subcylindric, with two and 

 a half polished, pale, latterly microscopically reticulate whorls, fol- 

 lowed by seven smooth or feebly striated whorls axially striped or 

 clouded with dark or light brown and opaque white. Umbilicus 

 closed, base attenuated, apex rather pointed ; peristome thin, simple, 

 yellowish white, broadly reflected, in the adult continuous over 

 the body ; parietal lamina; short, compressed, axial lamina low. in- 

 conspicuous ; the base of the last whorl sometimes strongly axially 

 striated. 



