MOLLUSCAN GENUS COCHLITOMA. 



253 



The crop is succeeded by a narrow continuation of the oeso- 

 phagus which fairly rapidly widens into the anterior part of the 

 stomach, which is thin-walled and crescentic. At the base of 

 the third whorl this gives off a large reniform, muscular sac 

 which may provisionally be regarded as the representative of 

 the coecum found in many Prosobranchs, Opisthobranchs, and 

 certain Basommatophora. This structure has been noticed by 

 Wiegmann (1898) in Achatina panther a. It is not present in all 

 Stylommatophora, but occurs in Bulimus (Borus) ovatus and 

 proximus according to Plate (1896). Owing to the fact that 

 the anterior part of the stomach opens close to the pylorus of the 

 intestine, we may fairly assume that the large muscular part 

 does represent the originally smaller caecum. The muscular 

 portion receives the posterior hepatic duct and is very thick- 

 walled, its inner surface being furnished with characteristic 

 ridges. A more detailed description of these organs is given 

 under v&r.fulgurata. 



(2) Circulatory and Respiratory System. 



As both animals bad been dead for some time previous to 

 dissection, it was impossible to make an injection of the circu- 

 latory system. This is all the more to be regretted as some 



Text-figure 3. 



CocJilitoma zebra var. obesa. 

 Anterior end of pulmonary vein. 



interesting results might be expected from the study of the 

 elaborate cerebral vascular system noticed when dissecting the 

 circumoesophageal nerve complex. The pericardium is under 

 one-third the size of the kidney, a smaller proportion than usual. 

 The auricle, as usual, is thin-walled and is attached to the adrenal 

 wall of the pericardium for about one-third of its length. It is 

 irregular in shape, but presents a broad end to the ventricle. 

 The latter is of a narrow, ovoid shape and is slightly shorter 



18* 



