106 CATALOGUE OF THE MOLLUSCA 



and sometimes inside dead bivalve shells. It is then very tran- 

 sparent and hyaline. Modiola marmorata is occasionally found 

 imbedded in the older individuals. This species may be the 

 Ascidia prunum of Macgillivray but not of Miiller. 



3. A. VIRGINEA, Mull. 



Ascidia oixdina, Macg. Moll. Aberd. 312. 

 Ascidia virginea, Forb. and Hani. Brit. Moll. i. 33, t. C, f. 4. 

 From the fishing boats at Cullercoats, rare. 

 The hyaline transparency of the outer tunic, and the bright 

 yellow and red markings of the inner, render this one of the 

 most attractive of our Ascidia;. The anal tube is much the 

 longest ; an unusual circumstance in this family. 



4. A. viTREA, Van Beneden 2 



Ascidia mtrea, Forb. and Hani. Brit. Moll. i. 35. 



On small sea-weeds brought in by the trawl-boats from a few 

 fathoms water. — J. A. 



We have not had the opportunity of seeing Professor Van Be- 

 neden's ^guYQs oi Ascidia vitrea, but our specimens agree very 

 well with the description of it in the " History of British Mol- 

 lusca," with the addition that the inner tunic is spotted with 

 yellow, and there is a yellow ring near the entrance to the bran- 

 chial sac. We had at first thought that this might possibly be 

 the young of the last, but it differs in being more ovate, and in 

 having the anal aperture small and little prominent, as well as 

 in the absence of red markings on the inner tunic. 



5. A. ALBiDA, Aid. and Hanc. 



Body ovate, white, transparent, and slightly tuberculated ; 

 attached laterally by a narrow base to small sea-weeds. Bran- 

 chial aperture lateral or subterminal, large but not very promi- 

 nent, the margin divided into eight points with intermediate 

 red ocelli. Anal aperture a little distant from the other, and 

 nearly half way down the body on the upper side ; largish, and 

 little prominent, with six red ocelli. Outer tunic hyaline and 

 colourless, covered with distant small tubercles. Inner tunic, 

 transparent white with bluish lines on the upper part ; below, 

 opake white slightly spotted with yellow. There is a large 

 opake white spot on the ganglionic prominence between the 



