1907] Bitter. — California Coast Ascidians. 21 



Styela milleri, n. sp. 



Superficial Characters. — Cylindric-ovoid, attached by a small 

 area at posterior end ; orifices both branchial the atrial somewhat 

 toward the dorsal side. No siphons, but orifices distinct, both 

 regularly four-lobed. Surface broken by a few irregular low 

 wrinkles anteriorly, by large patches of indurated or warty thick- 

 enings posteriorly ; the area of attachment bearing many short 

 filamentous processes. Color yellowish brown, the warty areas 

 darker. Length 22 cm., thickness 1.2 cm. Test very thin but 

 parchment-like, readily detachable from the mantle ; dull white 

 on inner surface. Mantle thin, muscle fibers uniformly distrib- 

 uted, longitudinal and circular, not disposed in definite bands, the 

 longitudinal generally somewhat stronger. 



Branchial Apparatus. — Siphons entirely wanting, both ori- 

 fices with clear-cut lobes. Tentacles of several lengths, about 

 thirty long and slender ones of nearly equal length, and probably 

 as many more shorter, but of unequal lengths. Dorsal tubercle 

 prominent, bearing the broad simple horse-shoe shaped hypo- 

 physis mouth. Branchial membrane with four folds on each side, 

 all broad except the one next the endostyle on the right side, two 

 of the folds on each side next the endostyle drawn out anteriorly 

 into long processes. Internal longitudinal vessels numerous and 

 large, the largest folds having eighteen or twenty on each face. 

 Transverse vessels consisting of a series of large and strong ones 

 of nearly but not quite equal size, and between many of these, 

 others very delicate, usually crossing the stigmata. Stigmata 

 long and slender, with the intervening vessels also very narrow. 

 Dorsal lamina a broad thin membrane not thin nor toothed, but 

 closely crimped. Endostyle heavy, irregularly tortuous through- 

 out. 



Intestinal Tract. — On the left side of the animal. Stomach 

 regular, elongate-melon shaped, the wall thrown into numerous 

 close, regular ridges or folds. A short duodenal section of the 

 intestine bent closely back upon the stomach, and from this a 

 n)uch longer rectal section having at about the middle of its 

 length a short flexure extending forward along the dorsal side of 

 the body almost to the atrial orifice. 



