58 PKOCEEDINGS OF THE MA.LACOLOGICAL SOCIEXr. 



The shell, which is remarkably stout, is brownish in colour, and 

 measures 13-5 mm. in length by 95 in breadth by 5 in height. 

 The beak is strongly inturned, and is reflexed upward. The 

 periostracum extends considerably beyond the anterior margin of the 

 calcareous part of the shell. 



In its internal anatomy this species so closely resembles T. nigrocincta 

 that a detailed description is unnecessary, but attention must be drawn 

 to the following special points of resemblance : the arrangement 

 of the gut-coils ; the absence of a crista aortse ixpon the intra- 

 pericardial part of the aorta; the large size of the reproductive 

 ducts and accessory glands — these are, in fact, even larger 

 than in T. nigrocincta, although the animal itself is considerably 

 smaller. The relative size of the several parts differs, however. 

 The albumen gland is larger in T. elongata, but the seminal vesicle and 

 spermatheca are smaller. Much importance should not, I suppose, 

 be attached to the size of these organs, for, no doubt, they vary 

 considerably in this respect according to the time of year, as in other 

 animals. 



