470 University of California Publications in Zoology [Vol.16 



exhaustive collecting and more extensive comparative studies will find 

 that the animals living farther to the north are specifically distinct 

 from those of the south on which we are chiefly relying for the estab- 

 lishment of the present species. In connection with the description 

 of Distoma lobata from Puget Sound, Ritter (1900) remarks upon the 

 similarity of lobata to a Distoma "widely distributed on the Cali- 

 fornia coast." The species occupying us is one of the group of 

 Californians to which reference was made in this quotation. 



These two Eudistomas furnish a good case of coincident distribu- 

 tion of two closely related species. That they are very much alike as 

 far as the zooids are concerned is obvious; and so far as we know 

 there is nothing at all differential in their habitats. However, we 

 would not be too positive on this latter point. Wider and more 

 detailed knowledge of the range of both may bring to light habit 

 differences which we do not now recognize. 



If Ritter (1900) is right in supposing the zooids of D. lobata to 

 possess five instead of three series of stigmata, the two closely allied 

 California species now before us seem to be considerably less similar 

 to the Puget Sound species than to E. plumbium Delia Valle, a 

 Mediterranean species. E. diaphanes in particular has much in com- 

 mon with the European species ; but diaphanes differs from plumbium 

 according to our present knowledge, in the larger number of branchial 

 tentacles, in the relatively longer esophagus, and probably in the 

 sharp division of the post-gastric intestine into sections. 



Didemnum carnulentum, n. sp. 

 PI. 39, fig. 11; pi. 44, figs. 57 to 59 



Superficial characteristics of the colony. — Thin and encrusting and 

 of considerable expanse, often half a foot or more ; thickness 4 mm. 

 or less. Color typically the pink of the human skin but varying to 

 opaque white. Position of the zooids indicated by small spots caused 

 by accumulation of spicules; these spots often appearing in double 

 rows which surround islands of gelatinous-appearing semitransparent 

 test and giving surface a reticulated appearance (pi. 39, fig. 11). 

 Spicules varying in diameter from .19 to .075 mm., their blunt rays 

 springing from a spherical nucleus (pi. 44, fig. 59) ; confined mainly 

 to uppermost stratum of colony. Bladder cells, usually polygonal 

 from mutual pressure but free from spicules, make up lower layer of 

 test. Branchial sacs of zooids embedded in upper spieule-bearing 

 stratum, their abdomens extending about halfway down into bladder- 

 cell stratum. Upper stratum of test having spaces in it which seem 

 to serve for communication with the common cloacal orifices, zooids 

 not being arranged with any reference to these openings. Cloacal 



