l Bitter. California Coast Ascidians. 29 



hility, however, that we have to do here with a membrane of the 

 Clavelina type, should not be forgotten, namely, one in which 

 the true membrane is without internal vessels. Were this the 

 truth the cilia criterion would be the only one by which the iden- 

 tification could be made. The view that cilia are absent may, I 

 think, be accepted with confidence since were they present there 

 should be no difficulty in observing them, for the specimens were 

 preserved in formalin while still in a fresh condition. It can 

 hardly be supposed that they were lost by post-mortem changes. 



Not knowing the orientation of the visceral mass within the 

 animal, I have said nothing in the diagnosis about the direction 

 of the major vessels of the branchial network. From the frag- 

 ment figured as 'connected with the visceral mass (pi. 2, fig. 28) 

 it is seen that they run lengthwise of the intestinal loop. As the 

 netw r ork is bound to the mantle of the vessels, there is no doubt 

 that the fragment is in its natural position as regards the intes- 

 tine. It would follow, if my assumption be true that the intra- 

 branchial tentacles are dorsal languets, that these major branchial 

 vessels run lengthwise of the body. 



The irregularity in both size and shape of the meshes is most 

 unusual. In this particular the species in hand appears to re- 

 semble Batlrypera splcndens Michaelson, more than any other 

 ascidian. This species, however, Michaelson regards, seemingly 

 with full justification, as related to Molgula. In other respects 

 there is little in common between our species and Bathypera. 



The problem of the affinities of this species would be difficult 

 even were our information about its adult structure not so im- 

 perfect. That on the whole it has more in common with 

 Corynascidia than with any other known genus may be gathered 

 from the descriptions and discussions already presented. The 

 several genera which it resembles to some extent are Abyssascidia, 

 Agnesia, Bathypera, Batliynoncus, Clavelina, Corynascidia, 

 Enpera, and HypobytJiius. The following tabulation of char- 

 acters of these genera will display most conveniently how BentJi- 

 ascidia michaelseni stands with reference to each genus: 



