32 University of California Puhlications in Zoology. [Vol.4 



have to look to Clavclina for the sac most resembling that of our 

 species. 



Station 4390, Lat. 33° 02' N.. Long. 120° 42' W., at the foot of 

 the continental shelf, off San Diego ; depth 2,182 fathoms, bottom 

 gray mud. 



It gives me pleasure to dedicate this new and in several re- 

 spects specially interesting addition to the ascidian deep-sea 

 fauna to Dr. W. Michaelsen, in recognition of his efficient studies 

 on both littoral and abyssal tunicate life. 



Ascidia clementea, n. sp. 



PI. 3, figs. 31 to 34. 



General Characters. — Somewhat pear-shaped, the small end 

 bearing the branchial orifice, turned to the dorsal side. Outline 

 rather regular, and surface even. Area of attachment at poste- 

 rior end, and to some extent on left side. Siphons distinct even 

 in contracted state; probably jorominent in life. Branchial 

 turned to the dorsal side; atrial on the dorsal side about mid- 

 way the length of the body. The lobes of both orifices large, the 

 ventral ones (uppermost from the bent-over position of the 

 siphon) of the branchial orifice, larger. Eight lobes to the 

 branchial orifice, and six to the atrial (pi. 3, fig. 31). Test semi- 

 transparent, thickness moderate and nearly uniform in all parts 

 of the body, rather soft. Length of largest specimen 11 cm., 

 greatest thickness 6 cm., distance between orifices 5.5 cm. 

 Musculature of mantle nowhere highly developed, wholly wanting 

 on most of the left side; the constituent fibers without regular 

 arrangement. 



Branchial Apparatus. — Branchial tentacles 75 or more, 

 simple, filiform, and situated on the edge of a hroad, rather thick 

 membrane or velum (pi. 3, fig. 33) t.c. Hypophysis mouth 

 horse-shoe shaped, the open end directed forward. The right 

 horn turned in slightly in the specimen examined. Gland rather 

 large, situated behind the hypophysis mouth a little more than 

 its own length. Ganglion long and narrow, the anterior end im- 

 mediately over the gland. The perihranchial groove narrow, out- 

 side the tentacular corona a distance about equal to the width of 

 the membrane that carries the tentacles. Dorsal lamina a broad 



