452 University of California Public-ations in Zoology [Vol. IG 



Styela gibbsii (Stimp.) 



Cynthia gibbsii, Stimpson, 1864, p. 159. 



Styela gibbsii, Herdman, 1898, p. 261. 



Styela gibbsii, Eitter, 1907, p. 23. 



Tethyum gibbsii, Ilartmeyer, 1909, p. 13-59. 



Styela (sens, restr.,) gibbsii. Huntsman, 1911, p. 131. 



This is one of the mo.st widely distributed ascidians of the west 

 coast of North America, it being now recorded from British Columbia 

 to San Diego, and from the littoral zone to a depth of forty fathoms. 

 On the coast of .southern California it appears to be rare along shore, 

 but fairly common clown to a depth of forty to fifty fathoms. 



Styela barnharti, n. sp. 



PI. 38, fig. 2; pi. 42, figs. 39 and 40 



Superficial characteristics. — Roughly elliptical in outline, almost 

 twice as long as broad, with branchial siphon sessile and directed 

 anteriorly ; atrial orifice a short distance below it on dorsal side. Each 

 orifice 4-lobed and surrounded by four flattened, smooth mammillae 

 corresponding to the lobes. Entire surface of the body mammillated 

 with large rounded protuberances, except for the flattened disc of 

 attachment (pi. 38, fig. 2). Test thick, firm, tough and semitrans- 

 parent. Color reddish yellow, the red being most intense on the 

 anterior end. JIantle strongly muscular, nuisculature consisting of 

 longitudinal overlaid by weaker circular bands. Circular muscles most 

 -strongly developed in siphonal regions. Size of largest animal in- 

 vestigated : length 4 cm., diameter 2.25 cm. 



Branchial system. — Branchial tentacles of .several sizes, about forty. 

 Atrial tentacles numerous, very small, slender, and tapering : in a 

 single circle on inner surface of a narrow vehnn wliich is folded up 

 against the wall of atrial siphon but not smoothly, the result being 

 that the atrial tentacles are inserted in the bottom of a groove formed 

 by a fold in the velum. The free edge of the velum and the rounded 

 edge of the fold, between and beyond which the tentacles extend, are 

 on about the same level. Spinules, each consisting of a single cell, 

 occur on inner surfaces of siphons ; rounded and toothed at their ante- 

 rior ends with striations corresponding to the teeth on the dorsal sur- 

 face ; nucleus of the cell situated toward the posterior end. Spinules 

 very similar to those of S. montereyensis. Dorsal tubercule horseshoe- 

 shaped with ends curled inward. Branchial sac with four folds on 

 each side. The distribution of the longitudinal vessels on the two 

 sides for the large individual was : 



6-ll>-9-14-G-14-S-15-6- R. 



^'^^'^ ^ Q^10-lQ-16-%-19-l-16-&- L. 

 Transverse vessels of four orders and regularly arranged. Order of 

 occurrence : 1—4-3—4-2-4-3-4-1 ; those of fourth order crossing the 

 stigmata. Dorsal lamina a plain broad membrane. 



