NO. 1989. ASCIDIANS FROM NORTHEASTERN PACIFIC— RITTER. 453 



(For fuller synonymy, see Van Name, 1912.) 



Thanks to Hartmeyer (1910) the delimitations of this species are 

 now pretty well established. 



The specimens at hand from Plover Bay belong, with little doubt, 

 to this old species. Although the number of tentacles is high — 

 about 18 or 20, while ecMnafa is said to possess 12 — the difference I 

 do not believe to be specifically significant. The difficulty, rather 

 common in this genus, of counting the tentacles; namely, of deter- 

 mining in some cases whether one has to do with a small tentacle 

 proper or a basal branch of one of the large members of the circlet 

 is encountered here. Examination of a specimen from Grand Manan 

 off the Atlantic coast of North America, recognized as the home of 

 ecJiinata, convinces me that the tentacle number and scheme do not 

 differ from those of the Bering Sea specimens more than they may 

 between specimens from either locality. This is in full agreement 

 with the recent description of the species by Hartmeyer and Van 

 Name. 



There are also three small specimens from Loring, Alaska, which 

 I assign to this species, though with somewhat more hesitation than 

 in the case of the Plover Bay animals. The spinulation of the 

 Loring specimens is certainly not typical, only comparatively few of 

 the spines presenting the regular ring of crowning secondary spines 

 so characteristic of ecMnata. A majority of the spines resemble 

 more closely the single axis spines of H. villosa and its congeners 

 than the radical spines of ecMnata. However, the stellate variety 

 does occur, particularly on one of the specimens; so on the whole I 

 have not considered the difficulty here sufiiciently great to invalidate 

 the identification. Again, well-defined dorsal languets occur in the 

 Loring animals, and this is perhaps a more serious obstacle in the 

 way of assigning them to this species than is the departure from the 

 type of the surface spines. But since the series of processes does not 

 extend all the way back to the posterior end of the lamina, there is 

 the same justification here as in the case of the Plover Bay animals 

 for the assignment made. 



Plover Bay, Siberia, 15 to 20 fathoms, W. H. Dall, 1880, 3 large 

 specimens. 



Loring, Alaska, Alaska Salmon Investigations, Albatross, Apr. 30, 

 1903. 



A single specimen from Aberdore Channel east of Alger Island, 

 Baldwin-Ziegler Polar Expedition, June, 1901. 



A smaU specimen irom. Albatross station 3213, southwest of San- 

 nak Islands, Alaska, 41 fathoms, is perfectly typical as to the spines. 

 I am unable to determine the number of branchial folds, but there 

 can be little or no doubt about the identification. 



