^ ANOMA. 



the mesocone very wide (Vol. XV, pi. 43, fig. 7, group of cen- 

 tral and lateral teeth; f. 6, the 9th lateral in profile, of A. 

 splendcns citrina). In the outer laterals of some species the 

 cutting edges are smooth, perhaps in part the result of wear 

 (Vol. XV, pi. 43, fig. 8, a lateral tooth of A. solida striatula). 

 Soft anatomy otherwise unknown. Type A. tricolor Pfr. 



Distribution, Jamaica (and the southwestern peninsula of 

 Haiti?). According to Gloyne (J. de Conch., 1872, p. 33), 

 the species of this group always live on plants. He collected 

 A. '' maugeri '' in great numbers in the parishes of Man- 

 chester and St. Anne, especially in the pimento or allspice 

 plantations. The species spread over the plateau of the west- 

 ern two-thirds of Jamaica, east to Mt. Diablo and Bogwalk, 

 and reappear in the extreme eastern part of the island, in 

 Portland parish. So far as we know, the intervening region 

 is without species of this genus, though this apparent discon- 

 tinuity may be due to deficient collecting in the Blue Moun- 

 tains. Only two species have been found in the East, A. 

 nigrescens and A. sinuata. 



The species are mostly restricted in distribution like nearly 

 all Jamaican snails; though a few seem to have a somewhat 

 wide range. Most of them have been differentiated into numer- 

 ous local races, distinguished merely by color, or sometimes by 

 other and more important characters also. There are both 

 dark and albinistic forms of many species completely alike 

 in all other characters. Examples of this are A. splendens 

 and citrina; A. nigrescens and A. n. rufilabris, etc. The 

 whole series seems to be composed of variable forms, in which 

 numerous sports occur, and are frequently perpetuated, per- 

 haps by the action of Mendel's law. Whether the striking 

 color-forms bear any direct or simple relation to their en- 

 vironments has not yet been observed. 



Owing to their great differentiation in color, the determina- 

 tion of species should be less difficult than in the related genus 

 Spirostemma. Most of them are herein figured for the first 

 time ; and it is hoped that the time and thought given to the 

 group have materially illumined a subject hitherto obscure. 



In A. solida var. striatula, I found 11 to 13 denticles on the 



