SOUK ASCIDIANS FROM THE ISLE OF WIGHT. 133 



lamina, directly opposite tlie cloacal aperture ; slit, ^ inch long and 

 smooth-edged. 



Ganglion hour-glass shaped, midway between the slit and the 

 dorsal tubercle. 



(Esophageal opening high up in the pharynx, between the slit and 

 the posterior third of the body. Behind it is a long smooth '^post- 

 buccal raphe '^ (see Heller's figure, 1. c). 



Branchial apparatus. — Meshes elongated transversely; stout 

 conical papilla at the junctions, provided with supporting ridges in 

 front and behind (fig. 13) ; intermediate papillge equally long, but 

 more slender than the primar}^ papillas ; six or seven stigmata in a 

 mesh J minute plications deep, the longitudinal furrows frequently 

 bifurcating. 



B. — The second individual differs from the one just described in 

 the external form, and in the absence of any malformation of the 

 dorsal tubercle and lamina ; in other respects it is closely similar to 

 the first specimen. 



Body of a compressed pyriform shape, the narrow end anterior, 

 attached by a circular area over the posterior half of the left side. 

 Dimensions — Length, 24^ inches ; Maximum breadth across middle. 

 If inches ; Thickness, f inch. 



Test very slightly furrowed, overgrown with algae and Polyzoa. 



Oral aperture terminal ; cloacal on the dorsal edge, slightly 

 nearer the posterior than the anterior end of the body. 



Oral siphon with vei'y short and obtuse lips ; no red pigment 

 upon either of the siphons. 



Tentacles forty in number, considerably longer than in the pre- 

 ceding specimen, irregularly arranged. 



Dorsal tubercle circular in shape ; aperture horse shoe-shaped, 

 the right horn cui'ved inwards. 



Epipharyngeal groove considerably longer, its lips gradually nar- 

 rowing and becoming continuous with the dorsal lamina. 



In all other respects this individual agrees with the former. 



Both individuals are mature and have ova and spermatozoa in 

 their generative ducts. 



I believe that in point of size these specimens have undergone a 



placed ill the posterior region of the pharynx, in Ascidia conchilega and Ciona \_canina] 

 intestinalis. The former species I have heen unable to examine, but in C. intestinalis 

 (preserved material) some individuals possess huge slits, through which the intestine con- 

 spicuously projects into the pharynx, while in other individuals no unusual apertures can 

 be made out at all. (Cf. Traustedt, loc. cit., p. 455. Heller, loc. cit., ii, p. 118, seems 

 merely to repeat Kupffer's statement. Roule, loc. cit., makes no reference to any excep- 

 tional openings.) I am inclined, therefore, to believe that in both these species Kupffer's 

 apertures arc accidental or artificial rather than natural. 



