6 University of California. Publications in Zoology. [VOL. 4 



far more suggestions of lobes than can be recognized in the 

 majority of the large number of individuals examined. There 

 can be no doubt about the presence of six lobes here. Whether 

 they stand for realities in the living animal, or are merely results 

 of retraction, I am not quite sure, but assume the former. The 

 condition of the atrial orifice is still more dubious. Usually in 

 an ascidian, where the lobes can not be made out by surface 

 examination, separation of the test from the mantle brings out 

 the true state of things. Applying this method here does not 

 help. Indeed the edge of the orifice, when thus freed, is even 

 more lobeless than when viewed from the surface. 



As will have been noticed from the diagnosis the branchial sac 

 is peculiar in several respects. The quadrilateral outline of the 

 infundibula is unusual in Molgulids. Frequently the infundi- 

 bula in this species are quite as broad at the inner end as at the 

 outer, and the notching or forking of many of them is quite a new 

 feature. The branchial folds, excepting the one nearest the endo- 

 style on each side, are broad and thin, and as a consequence the 

 infundibula are unusually flattened. The two folds adjacent to 

 the endostyle are so thin as to be easily overlooked. The small 

 size and irregularity of the stigmata is another peculiarity. One 

 may examine the whole area of a branchial membrane without 

 noticing more than the slightest inclination to curvature among 

 the orifices. In other individuals a pronounced tendency of this 

 sort is seen, some of the stigmata being curved to a quarter or 

 even a half circle. Again, the membrane itself is unusually thick 

 and heavy in the infundibula. and generally the stigmata are here 

 considerably smaller than in other parts of the sac. 



AVhat I interpret as the "renal organs" are rather insignifi- 

 cant as compared with these structures in many other Molgulids. 

 As mentioned hi the diagnosis, they are situated on the inner sur- 

 face of the mantle in the vicinity of the gonads. The largest one 

 observed, in a large specimen, was not more than 2 mm. across. 

 It consisted of a peculiar meandered folding of the epithelial 

 layer of the mantle, the cells of which, though somewhat larger 

 than those of the adjacent parts, had seemingly little in common 

 with the tissue characteristic of the renal organ of the Molgu- 

 lidae. But little coloring matter has been observed in any of these 

 structures in this species, and no vesicles have been seen. 



