PROF. W. A. HEEDJIAN ON" BRITISH TUNICATA. 431 



Notes on Eritisli Tunicata. — Part II. Bj W. A. Herdman, D.Sc, 

 F.H.S., Professor of JNTatural History in University College, 

 Liverpool. 



[Eead 15th June, 1893.] 



(Plates XXXIII.-XXXVI.) 



During the Session of 1880 I laid before this Society the first 

 part (dealing with the family Ascidiidge) of a paper on British. 

 Tnnicata, a group of animals vrhich I had shortly before com- 

 menced to study systematically. I hoped at that time that 

 further parts would have followed in rapid succesj^ion ; but 

 various circumstances, and chiefly my having undertaken the 

 examination of the large ' Challenger ' collection, prevented me 

 from finishing any other families of the British forms ; and it is 

 only now, after the lapse of thirteen years, that I have a further 

 instalment of notes ready. This part falls naturally into two 

 sections : — (1) Some corrections of my former paper, and my 

 views as to some other British species of Ascidiacea described 

 long ago by Forbes, Alder and Hancock, and others ; and (2) 

 my notes on some of the British Cynthiidae. 



I. AsciDiiD^ (Supplementary*). 



With the fuller knowledge I now have of variation in the 

 Tunicata, and after the experience of the last thirteen years in 

 examining specimens of the genus Ascidia,! am inclined to thit>k 

 that I laid too much stress upon minute structural characters in 

 Part I., and described as new species several forms which it 

 would be better to regard as varieties. I think that my A. lata 

 may be merely the common A. mentula, although it difi'ers from 

 the usual form of that species in the small number (16 to 20) 

 and size of the 'tentacles. The usual number of tentacles in 

 A. mentula is about 60 ; but I have found only 16 in a specimen 

 8 cm. long, and Garstang has recorded 18 ; while Traustedt, on 

 the other hand, gives 78 to 85 as the number in Mediterranean 

 specimens. 



My A. fusiformis may also be merely a variety of A. mentula ; 

 it has, however, a neater and more slender and fusiform shape, 

 an unusually small number of stigmata in each mesh (three, 



* For former paper see Journ. Linn. Soc, Zool. vol. xv. p. 274. 



