SOME ASCIDIANS FROM THE ISLE OF WIGHT. 145 



lamina, directly opposite the 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. a). 



Branchial apparatus. — Meshes elongated transversely ; stout conical 

 papillae at the junctions, provided with supporting ridges in front and 

 behind (fig. 13) ; intermediate papillae equally long, but more slender 

 than the primary papillae ; six or seven stigmata in a mesh ; 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 very short and obtuse lips ; no red pigment upon 

 either of the siphons. 



Tentacles forty in number, considerably longer than in the preceding 

 specimen, irregularly arranged. 



a considerable body of water from tbe pharynx into tbe cloaca, and thus to 

 effect the desired object more thoroughly than is possible when stigmata 

 exist alone. 



Kupffer has also recorded the existence of paired pbaryngo-atrial slits, 

 symmetrically placed in the posterior region of the pharynx, in Ascidia 

 conchilega and Ciona \_canina] intestinalis. The former species I have been 

 unable to examine, but in C. intestinalis (preserved material) some individuals 

 possess huge slits, through which the intestine conspicuously 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 are accidental or artificial rather than natural. 



K 



