128 BULLETIN 181, UNITE© STATES NATTOlNlAiL MUSlEUM 



varians Ads." No. 14, come from Accompong Town, St. Elizabeth 

 Parish. Adams credits them to Chitty as donor. Our specimens 

 were collected by Orcutt at Maggotty, St. Elizabeth Parish, about 5 

 miles south of Accompong. 



The specimen figured, U.S.N.M. No. 535983, comes from Maggotty, 

 St. Elizabeth Parish, It has 4.5 whorls and measures: Height, 12.0 

 mm.; greater diameter, 17.0 mm.; lesser diameter, 13.0 mm. These 

 meet most nearly the measurements cited by Adams. There are, how- 

 ever, larger individuals obtained at the same locality. One of these 

 has 5 turns and measures: Height, 14.8 mm.; greater diameter, 21.4 

 mm. ; lesser diameter, 16.2 mm. 



This species belongs to the group in which the basal sculpture near 

 the aperture consists of parallel, retractively slanting cords. This 

 character it shares with A. (O.) ruber (Chitty), from which it diflfers 

 in having much feebler sculpture on the latter portion of the spire 

 as well as the base. 



APEROSTOMA (CYCLADAMSIA) SEMINUDUM (C. B. Adams) 



Shell varying greatly in shape, which ranges in outline from 

 depressed-helicoid to subglobular. The color is also decidedly vari- 

 able, ranging from unicolor to banded, the light area usually being 

 flesh colored or buff, the darker chestnut-brown. The sculpture is 

 likewise immensely variable. The nucleus is small, usually consist- 

 ing of a turn or a turn and a half, which is smooth. The succeeding 

 postnuclear whorl is marked by finely, retractively curved, rather 

 closely spaced axial riblets, and from there on the remaining whorls 

 show rough lines of growth and numerous wrinkles, malleations, 

 and pittings. The strength of these elements varies very materially. 

 In some specimens they become decidedly enfeebled toward the pe- 

 riphery of the last turn; in others, they remain conspicuous. The 

 suture is moderately impressed. Periphery well rounded, smooth 

 in some individuals ; in other individuals, pitted. Base well rounded, 

 openly umbilicated, the umbilicus varying materially in size. In 

 one of the races it is exceedingly broad, while in another it is quite 

 narrow. A strong keel marks the outer limits of the umbilicus. 

 The umbilical edge of this keel is deeply impressed. The base varies 

 materially in sculpture; in some the posterior half is practically 

 smooth; in others, it is strongly pitted and decidedly rough. The 

 umbilical wall is marked by strong riblike incremental elements. 

 The aperture is subcircular, somewhat angulated at the posterior 

 angle; in some individuals there is a decided sinus on the outer lip 

 a little below the summit; in others it is absent. The columellar 

 wall is slightly excavated. Operculum typically cycladamsid, but 



