1907] Fitter. California Coast Ascidians. 27 



transparent that fragments, even after having been in preserving- 

 fluids for many months, can be seen in a glass of water only with 

 considerable difficulty. I do not recall having examined the test 

 of any other ascidian in which so few cells are present, Further- 

 more their regularity of form and size is exceptional. They pre- 

 sent almost none of the elongations, stellations, and other irregu- 

 larities common in most ascidiaus. 



In addition to the general statement about the course of the 

 muscle bundles of the mantle, it should be mentioned that in 

 limited areas, probably though not certainly, in the vicinity of 

 the orifices, bundles at right angles or nearly so, to those already 

 described, are present. 



In the diagnosis I have neglected to mention the tuft of 

 tentacles situated within the branchial sac between the esophageal 

 and anal orifices (pi. 2, fig. 28). My reason for this was my 

 doubt about the nature of the organs. The most probable sug- 

 gestion that can be made is that they are dorsal languets. Their 

 closely grouped condition, their restriction to the small area near 

 the esophageal orifice, and their slenderness, make, however, their 

 interpretation by no means certain. But a still greater difficulty 

 in the way of the suggestion is their position between the esopha- 

 geal and anal appertures. Assuming them to be dorsal languets 

 would involve the supposition that the median dorsal line of the 

 animal passes between these orifices. This assumption I make 

 on the evidence furnished by Corynascidia in this particular. I 

 recognize, however, that the evidence is far from sufficient to 

 establish finally the truth of such an assumption. In the one 

 known species of Coryanascidia, C. Suhmi Herdman, the "esoph- 

 agus opens." according to Herdman 's description, "on- the dorsal 

 edge," and the rectum "runs anteriorly in close contact with the 

 stomach and intestine." Thus the dorsal line in this species is 

 near enough to the two orifices to warrant the assumption I have 

 made. The tentacles are not only very slender but they are also 

 very thin walled and delicate. 



Of the several other remarkable features about this ascidian, 

 1 may next speak of the dorsal tubercle and hypothesis. PL 2, 

 fig. 29, shows the region where these structures seem quite cer- 

 tainly to have been situated. As a matter of fact, however, I 



