ASCIDIA MOLLIS. 93 



protuberant or tubular ; the branchial one is terminal 

 and the anal more than half-way down the body, and 

 at some distance from the ventral margin. 



The test (Plate V, figs. 1-3, and figs. 18 and 24 in 

 text) is of a blackish colour more or less tinged 

 with brown or blue, it is thick, transparent, smooth, 

 glossy, and soft to the touch, and is somewhat irregu- 

 larly and obtusely lobed. The blood-channels (PL V, 

 fig. 4) are numerous, the twigs being rather slender 

 with the extremities much and suddenly enlarged, 

 rounded, and of a crimson colour, dotting the surface 

 all over with brilliant points, which are conspicuous 

 towards the apertures ; the twigs are pale crimson, the 

 stems yellowish. 



The mantle (PI. V, figs. 5 and 6) is rather delicate and 

 has numerous, fine, muscular fibres running in various 

 directions, the transverse ones prevailing. The tubes 

 are short, but distinctly developed, with the aperture 

 red or crimson ; the branchial one is exactly terminal, 

 the anal is more than half way down the side, and is 

 turned towards the dorsal margin. 



The branchial sac (PI. XVII, fig. 5) extends a little 

 way behind the visceral mass and is minutely plicated ; 

 the primary vessels are rather distant and are pretty- 

 regularly dispersed ; the secondary vessels are long, and 

 the stomata rectilinear with the extremities rounded. 

 The longitudinal bars are stout ; the papillae at the 

 intersections of the meshes are large and conical, the 

 intermediate ones being more slender, but of nearly 

 equal length ; the papillary membrane is rather incon- 

 spicuous. The external vessels in connexion with the 

 branchial ties and primary channels are well developed 

 and form a reticulation at the outside of the sac or sill, 



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and are studded all over with stoutish conical papilla?. 

 The oral lamina (PI. XIX, fig. 4) is much narrower 

 than usual and is strongly ribbed on the right side ; the 

 left side is almost smooth ; the maro-in is strono-ly 



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pectinated. Below the mouth the lamina is so 

 narrow that it is difficult to determine whether it is 



