INTERNAL ANA1X)MY. 325 



small spines is also borne on a slightly raised and thickened disc, but they are 

 so inconspicuous that they are not represented in Plate 10, fig. 1. 



Liver and intestine. — The posterior visceral mass, made up of the remain- 

 ing portions of the alimentary tract and the ovotestis, occupies nearly the whole 

 of the body-cavity behind the head. Its ventral surface is convex, rounded 

 behind and in front, the black hver contrasting strongly with the Ught yellow 

 intestine and the reproductive gland. The dorsal surface is deeply faceted 

 with irregular depressions, caused by the pressure of the overlying organs, 

 notably those of the reproductive system. 



At the posterior end of the third stomach, a series of low ridges in its inner 

 layers converge toward the opening of the intestine. This portion of the diges- 

 tive tract is imbedded in the hver, occupying a deep groove in its surface. The 

 intestine passes into the right side of the hver, curving downward to its ven- 

 tral surface, across which it passes to the left anterior margin, thence up to the 

 dorsal surface, across which it passes obliquely backward, thence downward 

 again in a loop upon the posterior surface between the hver and the ovotestis, 

 returning after describing this curve to the right ventral side, whence it passes 

 upward and backward to the anal opening at the base of the siphon. It thus 

 forms in general a wide loop from below upon the left and dorsal surfaces, a 

 disposition correspoiiding closely to that found in Tethys. The total length 

 of the intestine is circa 300 mm., and its average diameter 7.0 mm. 



At the posterior end of the third stomach, below and to the left of the 

 pylorus, a spacious bihary cavity opens into it by a large channel. Into this 

 cavity in turn open numerous bile-ducts, which ramify out into the poorly 

 defined lobes of the hver. From the left of the bihary chamber the strongly 

 curved hepatic caecum extends, approximately 25.0 mm. in length. Owing 

 to the softened condition of the inner walls of this region the longitudinal folds 

 dividing the lumen of the caecum and their relations to the bihary chamber 

 and the intestine could not be made out clearly, but they appeared to be sub- 

 stantially the same as in Tethys (MacFarland, 1909, p. 44). 



The whole ahmentary canal, with the exception of the oesophagus, was 

 quite uniformly distended with coarse detritus of an algal nature, mixed with 

 considerable sand. In the intestine the latter was especially abundant, the 

 organ being crowded full with it. 



Reproductive System. — The reproductive system of Dolabella is com- 

 posed of the following parts, which will be described in the order given. 



1. Ovotestis. 



