ASCIDIA PLANA. 



95 



with numerous blood-channels. Mantle rather deli- 

 cate, with the apertures not much produced. Tenta- 

 cular filaments closely set, numerous, rather stout and 

 long. Branchial sac not quite so wide as the visceral 

 mass, with short rounded papillae at the intersections 

 of the meshes, and small intermediate ones on the 

 longitudinal bars. Oral lamina rather wide, ribbed, 

 and pectinated. 



Length upwards of two inches. 



Hal>. [Below tide-marks ?] 



FIG. 19. Ascidia plana. Natural size. 



ENGLAND. Hastings, Sussex [, dredged] (Pn 



CHANNEL ISLANDS. Guernsey (Alder). 



First record. Hancock, 1870 ; coll. Bowerbank 



[18(35]. 



The test of this very distinct species (fig. 19), which 

 has probably been confounded hitherto with A. inrntnl<t, 

 is thick, smooth, and firm, and the blood-channels (PI. 

 VI) can be distinctly observed in its hyaline, cartila- 

 ginous substance ; they are of a yellowish flesh-colour, 

 as seen in specimens in spirits, and are much sub- 

 divided, the terminal twigs being long and smaller so 

 as to be fusiform ; they are usually turned backwards ; 

 the extremities are rounded or only slightly pointed. 



The mantle is rather delicate, and in preserved speci- 

 mens exhibits in a remarkable manner the vascular 

 reticulations filled with dark brown blood-corpuscles. 



