284 ZONITIDJS. 



thickened, forming a sharp angle with the basal margin of the 

 peristome, and with a notch at the angle from which a keel rune 

 round the umbilicus. 



The animal (taken from Stoliczka's description of S. calias, 

 ? S. schistostelis) is fully retractile within the shell. The foot is 

 elongate, very narrow, with a distinct peripodial groove, the 

 posterior end obliquely truncate, occupied by a large high gland, 

 above which is a distinct horn-like appendage. The sole has 

 two longitudinal grooves dividing it into three subequal parts, 

 the middle rather narrower than the other two. Eye-pedicels 

 about half the length of the body : tentacles about one-fourth the 

 length of the eye-pedicels. 



Mantle conspicuously thickened near the margin. The left shell- 

 lobe is very large, entire, reflected over the edge of the outer 

 lips of the shell and below considerably produced. The right lobe 

 is divided into two parts : the upper is linguate, narrowly produced 

 and covering the base of the shell, partially also extending on to 

 the upper surface of the penultimate whorl, as in Macrochlamys ; 

 the lower portion is shorter, somewhat folded and reflected over 

 the columellar lip. The dorsal lobes are well developed and entire. 

 Genital opening at the upper somewhat outer base of the right 

 eye-pedicel. 



The general anatomical structure offers nothing very peculiar. 

 The kidney is an elongate, rather granular than plicated gland, 

 placed at the side of the heart ; it possesses a special long duct 

 accompanying the rectus and terminating a little short of the 

 anus. 



[Stoliczka thus describes the genitalia : 



" The genital organs chiefly occupy the anterior part of the 

 body. The arrow-sac is short and thick, with an enclosed, thick, 

 pointed papilla. The uterus, accompanied by the prostata, is very 

 long, thick, the former has a yellowish colour with a greenish 

 tinge, the latter is purely white ; terminal albuminous gland of 

 moderate size, slightly thickened; hermaphrodite gland large f 

 rather flatly depressed, connected with the uterus by a long 

 twisted duct. The vas deferens branches off a short distance from 

 the hermaphrodite opening : in about three-fifths of its length 

 from its origin it has a long pointed appendage, consisting of 

 strong tissue, filled with minute, elliptical, calcareous secretions ; 

 this appendage is attached by a special muscle close to the place 

 of attachment of the arrow-sac ; the last two-fifths of the vas 

 deferens gradually widens and towards the end the simple tube 

 consists internally of remarkably soft muscular tissue, but there is 

 no papilla present. The receptaculum seminis is a globular gland, 

 attached to a long slightly twisted string, originating from the 

 oviduct quite close to the hermaphrodite opening." 



It is apparent from this description and the figure that 

 accompanies it that these organs were not at their full state of 

 development, and were long and string-like in appearance. Those 

 dissected lately by me were in a much more advanced stage (see 



