88 



(of tliis work), wLicli \Yill therefore take the name of Spiraxis inn- 

 sitata Ad. ; and the two following species. Like many other of the 

 species of small land shells of Jamaica, the individuals are extremely 

 rare. 



Spiraxis aberrans. Shell elongate, nearly cylindrical in the lower 

 half : pale horn color, subtransparent : with microscopic transverse 

 rather distant stride : apex rather obtuse : spire with the outlines mod- 

 erately curved : whorls a little more than six, slightly convex, with a 

 distinct suture : aperture ovate, acute above : labrum sharp, well ex- 

 curved, projecting a little in the upper half: columella with a mode- 

 rately developed spiral lamella. This is probably identical with 

 Achatina aberrans Pfr. 



Mean divergence about 13°; length of spire .21 inch ; total length 

 .28 inch; breadth .0G5 inch. 



Spiraxis costulosa. Shell elongate-conic : whitish or horn col- 

 ored : with thirty-five to forty obtiige approximate transverse ribs : 

 apex obtuse : spire with the outlines almost rectilinear except near 

 the apex : whorls seven and one-half, very convex, with a deep suture ; 

 last two or three whorls with a spiral constriction on the middle, which 

 gradually increases to the labrum, which is much indented by it : col- 

 umellar lamina large. 



Mean divergence about 13^; length .175 inch; breadth .04 inch. 



Description of Jamaicia, a new subgenus of Cyclostoma. By C. 

 B. Adams. March. 1850. 



Cyclostoma t. Choanopomiformi, apertura orbiculari, margine sim- 

 plici : operculo extus spiraliter lamellifero, et maxime convexo, intus 

 laevi et maxime concavo. 



The shell resembles the more typical species of Choanopoma, but 

 has the peritreme simple, with the edge not much sharpened. The 

 operculum is extremely convex externally and concave within ; it has 

 a spiral lamella, and its striae of growth are lamelliferous. The only 

 species known to us is described below, under the name of Cyclostoma 

 anomalum. 



Notes on certain species of the land shells of Jamaica. By C. B. 

 Adams. March. 1850. 



Some varieties of Helicina IMlandi occur, in which the shell is 



