-1917] Eittcr-Forsijth: Ascidiaiis of Soutlicnt California 471 



orifices comparatively few in riumber and large ; branchial orifices 

 small openings in center of spots caused by closely set spicules. 



Zooids (pi. 44, fig. 57). — From 1 to 2 mm. long, depending upon 

 thickness of colony ; made up of thorax and abdomen. Mantle with 

 no muscle fibei-s visible. Color orange. 



Branchial system. — Branchial siphon with .six distinct, usually 

 pointed lobes, located in middle and anterior part of branchial sac. 

 Atrial siphon a plain round opening on dorsal side opposite middle 

 of sac. Branchial sac with four series of stigmata, each having about 

 six in a half -series ; stigmata elliptical. Endostyle proportionately 

 very broad. Dorsal languets three. Branchial tentacles eight, very 

 small. Two strong muscle bands from dorsal part of branchial sac 

 continue to near the recto-esophageal collar where they terminate in 

 a free process {ni.b., pi. 44, fig. 57). 



Digestive system. — An elongated loop with arms closely applied 

 but open at bend. E.sophagus (p., pi. 44. fig. 57) proportionately large, 

 emerging from middle posterior part of branchial sac ; often as much 

 as three times the length of sac. About two-thirds of its length from 

 sac. esophagus bound to rectum by a band (e.c., pi. 44, fig. 57). 

 Stomach (s., pi. 44, fig. 57) almost globular with smooth surface; its 

 long axis slightly inclined to that of zooid. First part of intestine, 

 about ecpial in length to stomach, connected by a portion equally long 

 but of smaller diameter with rectal arm of loop ; anus very near atrial 

 opening. 



Reproductive system. — Large undivided testis situated on left side 

 of intestinal loop ; on its rounded mound-like surface is the coiled vas 

 deferens {v.d., pi. 44, fig. 57), coil having six turns. Ovary, usually 

 containing one large egg and several very small ones, located between 

 stomach and testis (pi. 44, fig. 57) ; ripe eggs almost as large as 

 branchial sac. No oviduct appears to be present and how eggs are 

 discharged is not definitely known. Large tadpoles found in the test 

 of some colonies. Budding the same type as that which will be 

 described below for Trididemnum della vallei. 



Breeding season. — Colonies containing many tadpoles in June, but 

 few or none in January and February. 



Habitat and distribution. — In littoral zone but never at limit of 

 high tide ; usually on under sides of rocks. Abundant at La Jolla and 

 on all rocky beaches of the San Diego region. Although this species 

 has not been found at any other point, in all probability this is due 

 to in.sufificient collecting. 



Type locality. — La Jolla, California. 



The specific name refers to the prevailing flesh color of the living 

 colonies. 



Didemnum carnulentum var. lacteolum 



PI. 40, fig. 2.3; pi. 44, fig. 60 



Superficial characteristics of the coZo»i/.— Encrusting and very 

 thin, never of the great extent of Didenmum carnulentum: 1 mm. and 

 less in thickness. Color pure white, due to numerous calcareous 

 spicules varying in size from .15 to .065 mm. (pi. 44, fig. 60) ; spicules 



