ZOOTECUS. 105 



as in Holospira and Cerion-, the diameter remaining more 

 constant for any one colony. The proportion of diameter 

 to length is therefore individually variable. There is a good 

 deal of local variation in size and texture, and hence a 

 superabundance of names. 



The group was instituted by Westerlund as a section of 

 Buliminus. Kobelt, in his great monograph of the "Buli- 

 minidce" also leaves Zootecus therein, though uncertain as to 

 its position. Bourguignat struck nearer the mark in refer- 

 ring the species 'to Rumina, for I find the dentition to be of 

 the Stenogyroid type. It is however not closely related to 

 Rumina, which differs markedly by its smooth, globose pro- 

 toconch and attenuated, cylindric, subsequent neanic whorls. 

 Riebeckia is perhaps the nearest akin to Zootecus. Opeas 

 and its brood belong to another line of differentiation. 



Captain Hutton found the large Indian form (pullus) to 

 be viviparous, three or four young shells lying in the oviduct. 

 I have confirmed this by opening dry shells of Z. insularis. 

 The young are ovate-conic, perforate, of two or three whorls, 

 and like the adults have the columella entire below. 



There seem to be only two well-marked species, but 

 Z. insularis has a multitude of local races: 



1. Z. CONTIGUUS (Reeve). PI. 26, figs. 19, 20. 



Shell elongately cylindrical, not umbilicated, whorls 9, 

 flatly convex, smooth, polished, fainttly impressed-crenulate 

 at the sutures; columella broad, vertical. Aperture minute, 

 margins thickened, reflected, joined above by a callosity. 

 Ivory-white. (Reeve). Length 12 mm. 



Island of Sokotra (Reeve) ; Abd-el-Kuri, under stones on 

 the peak Gebel Saleh, 800-1500 ft. elevation (H. 0. Forbes). 



Bulimus contiguus RVE., Conch. Icon. v. pi. 79, f. 582 

 (Sept., 1849). Buliminus (Mastus) contiguus (Rve.) SMITH, 

 Natural History of Sokotra and Abd-el-Kuri, p. 152 ; 1903. 

 Bulimus teres PFR., Zeitschr. f. M'alak. 1849, p. 90 (Nov., 

 1849). B. contiguus Rve., PFR., Conchyl. Cab. p. 253, pi. 68, 

 f . 14, 15 ; Monogr. iii, 403 (description of teres repeated un- 

 der the name contiguus). 



