THE ASCIDIANS 245 



The two considerations of most weight in assigning the species to 

 Distoma are, first, the deep and broad siphonal lobes, and, second, 

 the fact that while many of the thoraces in the colony are distinct most 

 of them are not at all free. Further study of more material, particu- 

 larly of young colonies and the process of budding, may reverse my 

 conclusion on this point ; for a few young blastozooids are present on 

 the specimens at hand, and these are at least as much isolated as the full 

 grown ones. Moreover, the large quantity of mesenchymatous food 

 material stored in the abdomen is probably rather more Distomid than 

 Clavelinid. 



Within the genus Distoma the general character of the colony re- 

 sembles considerably that of D. laysani^ recently described by 

 Sluiter,' from Laysan, South Pacific. The resemblance goes no far- 

 ther, however, for the zooids are very different in the two, D. lay- 

 sani being much smaller, having a very inconspicuous, smooth- 

 walled stomach and only three rows of stigmata. On the whole D. 

 pulchra is probably more closely related to D. adriaticum v. Drasche 

 than to any other known species, though the two really have very 

 little in coinmon. The colonies, though pedunculated in both, are very 

 different. Adriaticum has fifty branchial tentacles and twenty-four 

 series of stigmata. 



According to Lahille D. cristallium Renier is the only other 

 species known in which the stomach wall possesses parallel folds. 

 This, however, is not a pedunculated form. 



Found at Yakutat Bay, on rocks at extreme low tide, June 20, 1S99. 

 One large and one small cluster of bunches in the collection. 



DISTAPLIA OCCIDENTALIS Ritter. 



Distaplia occidentalis Banxroft, Bull. Mus. Comp. Zool., Vol. xxxv, No. 4, 

 p. 59, 1899. — Ritter, Annals N. Y. Acad. Sci., Vol. xii, No. 14, p. 

 609, 1900. 



Although the identification of the specimens at hand with this wide- 

 ranging Pacific Coast Distaplia^ is doubtful for several reasons yet the 

 species is so exceedingly variable and the quantity of material of the 

 Alaska form now available for examination so small that I do not feel 

 justified in regarding the differences as of more than individual value. 



The two most important differences that I note are the denser, more 

 muscular thorax of the northern specimens and the greater distinct- 

 ness of the folds of the stomach wall. 



A single small colony was dredged in Kadiak harbor, July 3, 1899. 



^Zool. Jahrb., Bd. xiii, 1S90. 



