102 UNITED STATES NATIONAL ]MUSEUM BULLETIN 251 



alternate regularly. Ciliated groove an oval opening, slightly elon- 

 gated longitudinally. Dorsal languets remarkably large, arranged 

 on the dorsomedian line; horizontal membrane well developed along 

 each transverse vessel. Stomach situated nearly at middle of con- 

 tracted abdomen, globular and smoothly surfaced. Hind stomach 

 orange, midintestinal portion somewhat greenish; both parts very 

 short, the boundary between them rather indistinct, especially as the 

 greenish coloration of the distal part of the latter fades gradually and 

 continues to rectum without any clear constriction or any remarkable 

 change of coloration or appearance of intestinal wall. Anus opens at 

 dorsoposterior corner of thorax, the margin divided very distinctly 

 into about 20 small lobes, some of which may be subdivided into 2 

 lobules. Testicular follicles small and very nmnerous, nearly 100; 

 matured ova in ovary also relatively abundant, approximately a dozen 

 in nn examined zooid. 



Embryos rather small, nearly oval in shape. Three attachment 

 processes, roundish in outline and with short but stout stalks; ar- 

 ranged in a triangle, left dorsal one situated slightly ventrally to the 

 right dorsal process (fig. 34^). Two pigment flecks of the sensory 

 organ arranged anteroposteriorly. Distal part of tail always held 

 between ventral attachment process and two dorsal ones. 



Kemarks. — The present specimens differ rather distinctly from 

 the original descriptions given by Sluiter in the situation of the 

 incubatory pouch and the appearance of the anus. Sluiter (1904) 

 states "Vorn bildet sie, links von Kiemensack, den oben erwahnten 

 geraumigen Brutraum, welcher ganz mit Embryonen gefiillt ist" 

 (p. 7) ; the pouch in the present specimens, however, is clearly situated 

 on the right side of the thorax, and this is the general situation of the 

 incubatory pouch in ascidians. In Sluiter's original specimens, the 

 anus seems to be situated more anterior than in the present specimens 

 and plainly margined as shown in his description "... welcher 

 halbwegs des Kiemensackes in den glattrandigen aber weiten After 

 miindet" (p. 8) . These differences are, however, very probabl}'- attrib- 

 utable to the strongly contracted state of Sluiter's original specimens, 

 under such unfavorable condition it is very difficult to find out exactly 

 the natural appearance of these organs. The present species differs 

 distinctly from Clavelina inoUuccensis in the following ways : (1) soli- 

 tary life of O. fecunda; (2) test is thick and hard even in the part 

 enclosing the thorax in C. fecunda., while it is voiy thin and soft in the 

 corresponding portion in C. molluccensis ; (3) thoracic, and also ab- 

 dominal longitudinal muscles are very strong, consequently all zooids 

 are found in a strongly contracted state in C. fecunda., while zooids of 

 C. molluccensis are found rather in an extended state; (4) margin of 

 anus is not cut into lobes in C. molluccensis., Avhile it is distinctly lobed 

 in C. fecunda. 



