ASC1DIA. 67 



are given off, the tubes are usually enlarged, and the 

 twigs terminate in rounded extremities which are more 

 or less inflated. 



In A. r iU(.'itfnla the dichotomous division of the tubes 

 is very obvious, and the enlargements or ampullae at 

 the junctions of the branches are greater than usual 

 and assume a triangular form. Oval enlargements also 

 frequently occur among the branches, which latter, 

 uniting, go to form two long slender ducts which pass 

 backward within the loop of the intestine, buried 

 amidst the vesicular substance already described, and 

 at length open through the left wall of the stomach 

 about midway between the cardia and pylorus, towards 

 the anterior margin. These two ducts come from the 

 middle portion of the intestine ; another duct, passing 

 from the lower portion, unites with one of those first 

 mentioned just before it sinks into the wall of the 

 stomach. 



In A. sordid a and A. srolrit the arrangement of the 

 parts of the hepatic organ is similar to that in the 

 above species. 



The reproductive organs are well developed in the 

 Ascidiae, and in all of them the sexes are combined, as 

 is usuallv the case in the whole class. The male and 



t/ 



female elements are, however, always secreted by 

 distinct organs, which are provided with their respec- 

 tive ducts. 



In A. sordida the ovary is composed of numerous 

 tubular branches which ramify in a radiating manner 

 over the left side of the looped portion of the intestine. 

 The oviduct passes through the loop, and, following 

 the curvature of the intestine, opens by the side of the 

 anus into the cloaca. The fas defer ens terminates 

 near the same point, and is adherent to the oviduct 

 throughout its course. In the vicinity of the ovary it 

 receives several much-attenuated branches from either 

 side of the intestine ; these divide dichotomously, the 

 ultimate twigs terminating in elongated and irregularly 

 lobulated vesicles, which are spread over the intestinal 



