If J"] Kitter-Forsytli : Ascidians of Southern Calif ornia 4-73 



Common eloacal orifices large and eomparativelj' few, scattered among 

 the numerous zooids. Test immediately around eloacal openings free 

 from spicules. Spicules of usual Didcmiium type but differing from 

 those of D. carnidentum in that the rays are distinctly longer and 

 relatively slenderer (pi. 44, fig. 56) ; size from .2 mm. to .08 mm., 

 confined mainly to surface layer of test, but sparingly present through- 

 out. Usually in preserved specimens branchial orifices marked by 

 white spots due to accumulation of spicules; these spots uniformly 

 and thickly scattered over surface of colony without definite arrange- 

 ment with reference to the cloacae. In expanded condition six branch- 

 ial lobes showing as clear oval spots in middle of each lobe near its 

 base. No bladder cells observed in test. 



Zooids (pi. 44, fig. 54). — Length 1 mm. or less; divided into thorax 

 and abdomen, the two being equal in size; esophagus and rectum 

 girdled by a constricting band about midway the length of zooid (pi. 

 44, fig. 54) ; placed at all angles to surface of colony. Ectodermal 

 processes, (e.p. pi. 44, fig. 54) given off from mantle near stomach, ex- 

 tending for varying distances into test, ending in pigmented swellings. 

 ]\Iantle very thin and delicate, a few weak, longitudinal and hor- 

 izontal fibers being visible over branchial sac. 



Branchial system. — Branchial siphon with six distinct lobes; atrial 

 orifice plain, at the end of a tabular siphon which protrudes from 

 middle of dorsal side ; its sphincter muscle strong and distinct. Three 

 series of stigmata, about ten orifices in first series, eight in second, and 

 seven in third; considerable area of unperforated branchial membrane 

 at both ends of sac. Endostyle straight and proportionately very 

 broad. Two dorsal languets placed at intervals between stigmatic 

 series. Two muscle bands in branchial sac, one on each side of mid- 

 dorsal line, course ventralward toward posterior end of sac and, meet- 

 ing each other behind sac between esophagus and endostyle, are car- 

 ried out into a blunt process with an epithelial covering, this process 

 penetrating into the test {m.b., pi. 44, fig. 54). Endostyle often arched 

 at both ends in preserved specimens, due to contraction of these mus- 

 cles. Branchial tentacles equal in length, variable in number, twenty 

 being found in one zooid ; about sixteen the usual number ( pi. 44, 

 fig. 55). 



Digestive system. — A loop in which the esophageal and rectal limbs 

 are closely applied, loop being wide and nearly circular. Recto- 

 esophageai collar almost midway the length of the esophagus. Stomach 

 almost globular, smooth-walled. First part of intestine, a little shorter 

 than stomach, tapering from large pyloric opening; connected by a 

 piece of about equal length but of much smaller diameter to rectal 

 arm of loop ; this latter of greater diameter than middle piece ; anus 

 opposite atrial orifice (pi. 44, fig. 54). 



Reproductive system. — Single conical mound-.shaped testis situated 

 on bend of intestinal loop on left side ; coil of vas deferens containing 

 six turns. The ovary, apparently consisting of single egg when ripe 

 as large as branchial sac : but in reality a small number of minute ova 

 always present. No oviduct found and the mode of escape of eggs 

 not known ; the relatively enormous eggs ( fully half the size of full- 

 grown zooids) after escape from ovary, scattered through test at 

 rather regular intervals in layer inunediately in contact with the sub- 



