170 Mr. J. Alder on the British Tunicata. 



shaped common excretory orifice, of great transparency. Branchial 

 apertures six-rayed. Thorax cylindrical, occupying more than 

 one-third of the length of the body. Abdomen rounded, simple ; 

 postabdomen about the same length as the thorax, slightly 

 pedunculated, and ending in a point below. Diameter of the 

 mass about three-quarters of an inch. 



This species was dredged by Mr. Norman on the haddock- 

 ground about six miles north of the Whalsey Lighthouse, Shet- 

 land. It is remarkable on account of its great delicacy and the 

 transparent funnel-shaped excretory orifices, which rise consider- 

 ably above the surface. 



Polyclinum cerebriforme, n. sp. 



Common body transversely ovate, depressed, pretty largely at- 

 tached, yellowish, the surface corrugated into folds like those of 

 the surface of the brain. Individuals irregularly disposed over the 

 surface ; systems few ; the excretory orifices rather small, circu- 

 lar, with the margin very slightly produced. Longest diameter 

 of the mass three-quarters of an inch ; shortest, about half an 

 inch. 



This is another of the species for which I am indebted to my 

 friend Mr. Norman, who procured two specimens, between tide- 

 marks, on the south side of Bantry Bay, in October 1858. It 

 is distinguished from Polyclinum aurantium by the folds of the 

 surface, as well as by its smaller and more circular common 

 apertures. The character of the individuals could not be satis- 

 factorily made out. 



Amaracium pomum, Sars. 

 Amaroucium pomum, Sars in Nyt Magaz. for Naturv. vol. vii. p. 155. 



Common body globose, subcartilaginous, yellowish -grey, sessile, 

 attached by a spreading base. Individuals straw-coloured, rather 

 large, set in numerous regular systems of from six to twelve, in 

 single series, round a prominent central orifice with a lobed 

 margin ; the lobes corresponding to the number of individuals. 

 Thorax yellow, pellucid. Branchial sac with ten to eighteen rows 

 of stigmata. Abdomen shorter than the thorax, oval ; stomach 

 brownish-yellow, areolated : postabdomen long, cylindrical, acu- 

 minated below. Diameter of mass various. Length of indivi- 

 duals neai'ly half an inch. 



A specimen of this fine species was sent to me by Mr. Mac- 

 donald, of Elgin, obtained from deep water in the Moray Firth. 

 It was much smaller than the Norwegian specimens described 

 by Prof. Sars, the mass not measuring more than an inch and a 

 quarter in diameter; but the agreement of its characters in 



