1907] Bitter. — California Coast Ascidians. 33 



iiieiiibrane witli imnierous ribs on its sides, and short processes 

 on its edge. Anteriorly the edge of the lamina is grooved for a 

 distance about equal to the length of the combined ganglion and 

 hypophysis gland (pi. 3, fig. 33). At its posterior end the lamina 

 pas.ses to the right of the mouth of the esophagus, and extends a 

 full centimeter behind this point, and from its extremity a shal- 

 low groove turns back on the lamina and extends forward to the 

 esophagus mouth. 



Inlcnnd loiigitudinal vessels of branchial sac all of one size, 

 and vniiformly distant from one another, armed with strong 

 papiJla.c at the crossings of the transverse vessels, and also with 

 smaller intermediate papillae. Spaces between the internal long- 

 itudinal vessels about equal to the distance between the transverse 

 vessels, so that the meshes are nearly square. A rather pro- 

 nounced horizontal membrane on the transverse vessels. Besides 

 the ordinary transverse vessels, a system of very large vessels, 

 or pipes (pi. 3, fig. 34), t.b.p., on the external surfaces of the 

 branchial membrane. These mostly running around the sac, but 

 with occasional anastomosing longitudinal pieces. Typically 

 about a dozen series of stigmata between two of these transverse 

 pipes, but sometimes fewer. The diameter of a pipe equal to the 

 space between two transverse vessels. 



The branchial membrane with deep, narrow pUcations, these 

 however not regular, and not involving the entire area of the 

 membrane. Where the plicae are not present, about seven stig- 

 mata between two internal longitudinal vessels. 



Digestive Apparatus. — Situated on the left side. The intes- 

 tinal loop wide and simple, there being a slight curve only in 

 the rectal part of the intestine. Stomach but little larger in 

 diameter than the intestine, which is of very uniform calibre 

 throughout its length. Wall of stomach with numerous, regular 

 well defined folds. Esophagus very small. Renal organ vol- 

 uminous, situated in the mantle, and covering over the entire 

 digestive tract, extending considerably beyond it all around. 

 Composed of a conglomerate of large clear vesicles, in the center 

 of each of which is a yellow green body (pi. 3, fig. 32, r.) 



Reproductive Organs. — Situated in the intestinal loop chiefly, 

 but the ovary extending behind it somewhat. The ovary a retic- 



