10 BULLETIN OF THE 



convexity is anterior ; it is transversely flattened close to the mouth, and 

 is a little compressed laterally, behind that portion. It is of a nearly uni- 

 form calibre throughout. It has quite a thin lining membrane, which be- 

 comes thicker, though still smooth, in the stomach, and quite thick and 

 longitudinally plicated in the intestine. The stomach is well differentiated 

 from the alimentary canal and intestine, and is of an oval shape. It is 

 embraced by the hepatic digitations, which are of a greenish-yellow 

 color, and empty into the stomach by four ducts. The orifices of these 

 ducts are of a compressed oval shape, obliquely inclined, and the anterior 

 pair, which correspond to the right and left anterior congeries of hepatic 

 digitations, are twice as large as the posterior pair, which similarly corre- 

 spond to the anterior lobes or bunches of digitations. The individual 

 digitations appear to be longer, larger, and less numerous than those of 

 W. australis, etc., as described by Hancock. They are traversed by 

 numerous ducts and bloodvessels, and the hepatic matter, when separated, 

 appeared to be of a granular consistency. Among the yellowish granules 

 in the hepatic matter, both before breaking it down and afterward, were 

 noticed certain darker granules, similar in general appearance to those 

 found in the ovary. The digitations are distinctly arranged in four groups, 

 of which the anterior pair are the larger. The upper and posterior sur- 

 face of the stomach is bare, and the arrangement of the mesentery and 

 the gastro- and ileo-parietal bands essentially agrees with the description 

 of the , same parts in other species of this group, as given by Hancock. 

 The intestine is twice as long as the oesophagus, of uniform calibre, and 

 perfectly straight. It leaves the stomach abruptly without any dilatation 

 of the portion adjacent to the latter organ, and reaches about half-way to 

 the dorsal valve. The heart is situated behind the junction of the stom- 

 ach and intestine. The termination of the intestine is abruptly rounded 

 off and not at all pointed. It is entirely closed, and is upheld by the 

 mesentery. It is also of a much darker color than the rest of the alimen- 

 tary canal, beiDg of a deep chestnut-brown hue. 



The great pallial sinuses and their ramifications in W. floridana are of 

 much less extent and disposed in quite a different manner from that which 

 obtains in W. australis. The haemal pallial system consists essentially of 

 four branches which are remarkable for their straight course and the pau- 

 city of their ramifications. The neural pallial system is very similar, with 

 a greater number of small sinuses about the perivisceral cavity, but in 

 both lobes the narrowness and small extent of the sinuses, as compared 

 with those of other species, is very marked, and the same is true with 

 regard to the ovaries. But a very few exceedingly delicate spiculce were 

 observed in the floor of the greater sinuses. The heart consists of a very 

 minute pyriform vesicle situated behind the intestine at its junction with 



