AMERICAN OPEAS. 191 



A set before me from Antigua consists of rather narrow 

 shells with delicate riblets, and a more tapering shape than 

 the types. 



In Haiti (pi. 27, fig. 54) this species is found at S. Domingo 

 City (H. Prime) and around Port au Prince (Henderson and 

 Simpson) . The shells are small, length 6.2 mm. with 8 whorls 

 to 8 mm. with 9y 2 whorls. The riblets below the suture are 

 very short, the rest of the surface being striate. This small 

 form imitates the Colombian examples described above. 



A variety with very strong, regular ribs (pi. 27, figs. 42, 43) 

 is before me from Caracas, Venezuela, collected by F. R. 

 Cocking in 1860. The shells measure about 8x3 mm., with 

 31/2 whorls, some being smaller. 



Mr. Smith states that specimens from Fernando Noronha 

 are more strongly costulate than the Brazilian specimens com- 

 pared (Journ. Linn. Soc. Lond. xx, p. 502). 



Bulimus oryza of Bruguiere, from Guadeloupe was probably 

 based upon this species, but the description is not wholly con- 

 clusive ; the number of whorls especially does not agree. 



Two forms described by Jousseaume from Caracas seem to 

 be referable to 0. beckianum, either as synomyms or varieties. 

 The descriptions follow. 



"Synopeas simoni. PL 27, fig. 40. Shell perforate, cylin- 

 dric-turrite, rather thin, slightly striatulate, waxy, marked 

 with small scattered whitish spots; spire elongate, turrite, 

 rather acute ; whorls 8%, convex, separated by a deep suture, 

 the last scarcely one-fourth the total length, rounded at the 

 base. Aperture oboval; peristome simple, unexpanded, the 

 columellar margin shortly spreading. Length 7, diam. 2.5 

 mm." (Jouss.). 



According to M. Jousseaume, this differs from 0. caraca- 

 sensis by the smaller size, less apparent striae, by the white 

 spots and narrower umbilicus. Four specimens taken, one 

 adult at the -colony of Tovar, the others young, at Caracas. 

 This is evidently identical with the form from Carthagena, 

 etc., which I have commented on above. 



The smoothness is an individual character, though colonies 

 where the average or majority of the shells are of the smooth- 

 ish type might be recognized by a varietal name. 



