Mr. J. Alder on the British Tunicaia. 165 



anterior end. Test thick, smooth, white, semitransparent, ad- 

 hering strongly to the mantle throughout. Mantle opake white, 

 with one or two blotches of red near the apertures. Tentacular 

 filaments linear (?). Branchial sac with four folds on each side(?); 

 ventral line smooth, inconspicuous. Breadth three-quarters of 

 an inch ; height one-third less, rising a little towards the ante- 

 rior end. 



A single specimen of this pretty species was obtained by Dr. 

 Bowerbank from the Diamond fishing-ground, near Hastings. 

 As the internal parts were partially decomposed, their character 

 could not be very satisfactorily made out. We know of no other 

 Cynthia, however, with which it can be confounded. In its 

 opaline and mammillated test it somewhat resembles a miniature 

 Ascidin mainmillata ; but, besides its generic difference, it like- 

 wise differs in form, and in the more numerous and smaller 

 mammillae. 



Cynthia violacea, n. sp. 



Body very much depressed or nearly flat, transversely ovate 

 or rounded in outline, and adhering by a broad expanded base. 

 Test slightly hispid, and completely covered with small grains 

 of sand. Apertures on rather long and slender tubes of a violet 

 colour, set very little apart, and nearly equally distant from both 

 ends. Diameter a quarter of an inch. 



Two specimens occurred to me on an old shell of Pecten Tnaxi- 

 mus among the rocks on Mrs. Hughes's Island, Menai Straits, 

 in 1852. 



Although, from its minuteness and delicacy, the internal parts 

 of this species could not be examined, there can be little doubt 

 of its distinctness from any other described Cynthia. The grains 

 of sand adhere so closely that they can scarcely be removed 

 without tearing the test, which is very thin. 



Cynthia grossularia, Van Beneden. 



The Ascidia nistica figured and described by Miiller in ' Zoo- 

 logia Danica ' contains two, if not three species, supposed by 

 him to be different stages of growth of one and the same animal. 

 Contmental authors have (and, I think, rightly) considered the 

 largest or adult form to be the Ascidia rustica of Linnaeus, 

 agreeing with his description " corpus oblongum, subcylindricum, 

 hrunneum." The supposed youngest form of Miiller is un- 

 doubtedly distinct, and is the species which English authors 

 have hitherto called Cynthia rustica. Having ascertained, how- 

 ever, from specimens sent me by the accompUshed author, that 

 Prof. Van Beneden's Cynthia grossularia is identical with our 



