280 DE. W. A. HEBDMAK OK BBITISH TTTNICATA. 



Phallusia virginea, Kupffer, Jahresberichte d. Komm. z. Untersuch. d. 



deutsch. Meere in Kiel, Tunicata, p. 210 (1874). 

 Ascidia sordida, Macintosh, Marine Fauna of St. Andrews, p. 55 



(1875). 

 Ascidia virginea, Heller, Untersuch. il. d. Tun. d. Adriat. u. Mittelm, 



ii. Abth., p. 7 (1875). 

 Phallusia virginea, Traustedt, Oversigto. d.f. Danmark, SfC.,Asc. simp. 



p. 45, in Vid. Medd. Nat. For., Kjbbenhavn (1880). 



M. Traustedt, in a paper published last summer, on the 

 Simple Ascidians from the coast of Denmark &c, Las placed 

 Ascidia sordida of Alder and Hancock as a synonym of Ascidia 

 virginea. In this I quite agree with him. A comparison of the 

 descriptions of A. sordida by Alder and of A. virginea by Kupffer 

 and Heller leaves no room to doubt that they are the same species. 

 It is rather curious, however, that Alder should have both names 

 in his catalogue ; he does not in his description of A. sordida } 

 as a new species, refer to A. virginea at all. 



A few points in regard to the characteristics of the species 

 still require to be discussed. The external appearance has been 

 fully described, especially by Alder and Heller. In regard to the 

 branchial sac, the absence of papillae (see PL XV. fig. 1) has been 

 noticed by Alder, Kupffer, and Traustedt, while Heller states 

 that the internal longitudinal bars are provided with small three- 

 cornered papillae. I have figured (PI. XV. fig. 2) a small portion 

 of the branchial sac seen from the outside, to show the appear- 

 ance presented by the longitudinal plication. The dorsal fold 

 is always described as ribbed transversely and smooth-edged. In 

 specimens from the Firth of Eorth, however, where what was 

 described by Alder as Ascidia sordida is very common in 4 and 

 5 fathoms, the margin is slightly but distinctly toothed, there 

 being several smaller denticulations between each pair of larger 

 ones, which are opposite the ends of the ribs. The tentacles 

 are described as being closely packed and about fifty in number. 

 This is considerably under what I have observed, which has 

 generally been about ninety ; they are rather slender, and are of 

 two sizes placed alternately. 



Ascidia tetjfcata, n. sp. (Plate XV. figs. 3-6.) 



External appearance. — Shape oblong, nearly quadrangular, 

 flattened laterally ; anterior end truncated, slightly narrower 

 than the almost straight posterior end ; dorsal and ventral edges 

 nearly straight and parallel. Attached by a narrow transverse 



