ASCID1A CAXIXA. 123 



Apertures reel, tuber'culated or echinated longitudinally, 

 the branchial terminal, the anal on a short tube at a 

 little distance below. Ocelli inconspicuous. Text thin, 

 sub-pellucid, yellowish white or horn-coloured, with a 

 tinge of red, finely hispid, minutely but irregularly 

 tuberculated and a little aculeated at the upper part. 

 Mantle red above and yellowish below, the intestine, 

 shining through, of a greenish colour. Tentacular 

 filament* short. Branchial sac with small papillae. 

 Oral lamina with a strong smooth plait. 



Leiif/tJ/ three or four inches. 



Hah.- ? 



EXULAXD. Solent Channel, Hants (Jain ex and 

 Forbes). [Falmouth, Cornwall (Codes, 1841)).] 



SCOTLAND. North Uist, Outer Hebrides (McLitosh). 

 Kirkwall Bay, Orkney (Forbes and Goodxir). 



IKELAXD. Strangford Lough, Down (Thompson). 

 Clew Bay, Mayo (Thompson, Ball, and Forbes). 



First record Thompson [1844]. 



The blood-channels enter the test near to its base, 

 and are confined to the lower portion, where there 

 are a few large trunks which give off a limited number 

 of slender branches, but none of them reach halfway 

 up the test, and the alternate twigs end in slightly- 

 enlarged elliptical casca. 



The mantle is very delicate, transparent, and but 

 feebly supplied with muscular fibres, which are irregu- 

 larly disposed. 



The branchial sac (PI. XVIII, fig. 5) is long and 

 extends to the bottom of the mantle, and has the 

 alimentary tube on the right side. The loop of the 

 intestine is considerably elongated in the upward or 

 antero-posterior direction, and the rectal portion is 

 rather long and wide. The branchial membrane is 

 rather delicate and minutely plicated ; the primary 

 vessels do not vary much in size, and are pretty 

 regularly disposed. The longitudinal bars stand well 

 up from the surface and are rather far apart, there 



