256 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Ascidiella griffini* n. sp. PL XII., figs. 1 — 3. t 



External appearance. Shape ovate, with the rounded 

 posterior end broader than the anterior, and the ventral 

 edge more convex than the dorsal. Attached by a small 

 area on the middle of the left side. Apertures both on 

 prominent siphons, branchial terminal, atrial a little way 

 down dorsal edge, both directed forwards. Surface 

 minutely roughened all over, with slightly larger pro- 

 cesses round the apertures. Colour warm brownish 

 grey, with a few rust-coloured markings. Length 6 cm., 

 breadth 4 cm., thickness 2 cm. 



Test of a soft cartilaginous consistency. Large vessels 

 ramify on the left side. 



Mantle fairly thick. Musculature well developed. 



Branchial sac plicated. Transverse vessels not all 

 the same size, but not regularly arranged. Meshes much 

 elongated transversely, and containing about 12 rather 

 slender straight stigmata. There are large blunt papillae 

 at the angles of the meshes, and also smaller intermediate 

 ones. No horizontal membranes divide the meshes. 



Dorsal lamina with well-marked transverse ribs and a 

 toothed edge. 



Tentacles long and slender, very closely placed, 60 to 

 70 in number, and of different sizes. 



Dorsal tubercle horseshoe shaped or cordate, with both 

 horns turned inwards. The nerve ganglion placed close 

 behind the tubercle, the pre-branchial zone papillated. 



Alimentary canal large, occupying at least four-fifths of 

 the left side, imbedded in the reproductive and renal masses. 



Locality : Off Port Townsend, Puget Sound, three 

 specimens. 



* I dedicate this species to the memory of Mr. B. B. Griffin, of Columbia 

 University, New York, who kindly accompanied me on my dredging exped- 

 ition' at Port Townsend. 



