THE ASCIDIANS 247 



the distomid type. Narrow esophagal-rectal portion about equalling 

 thorax in length. Stomach of moderate size, somewhat shorter than 

 branchial sac ; longer than broad, the longer axis forming an angle of 

 about 45 degrees with main axis of animal ; external surface of wall 

 smooth, but inner surface marked by a close, rather regular reticula- 

 tion showing through, due to low narrow folds in the wall. Reticula- 

 tion more pronounced in fully grown zooids (p1. xxix, figs. 26 and 27). 



Reproductive organs. — Ovary situated in part on the right side of 

 the intestinal loop but chiefly behind it. Ova few but very large. 

 Testis not seen. No einbryos in the specimens at hand, consequently 

 presence or absence of brood pouch not determined, facts probably in- 

 dicative of immaturity of specimens. The presence of well-developed 

 ectodermal appendages of the mantle in most of the zooids indicative 

 of same conclusion, according to the statement of Bancroft,^ that in 

 D. magnilarva and D. occidentalis these structures are found only in 

 the young. 



The close general resemblance of the zooids of D. co7ifusa to the typical 

 Disiotna zooid is striking indeed. So far as I am aware, no other 

 Distaplia possesses the long straight esophagus found here. 



For a time I was much disposed to identify the species with D. liv- 

 ida Huitfeldt-Kaas (Sars), of the Norwegian coast, and there can be 

 no doubt about the close relationship of the two forms. It is quite 

 possible that further study of more specimens from both Alaska and 

 Norway, will prove them to be the same. At present, it seems clear 

 that the shortness of the zooids of D. livida (4 mm. according to 

 Huitfeldt-Kaas) indicates that the peculiar, long, straight esophageal- 

 rectal stretch of the intestine is not present in that species. Further- 

 more, Huitfeld-Kaas ^ speaks of the colonies of D. livida as being 

 " composed of very soft, thick, irregular, lobed lamellae with a maxi- 

 mum area of 2.5 cm. and a thickness of about 7 mm. 



Dredged in about twenty fathoms, Kadiak harbor, July 3, 1S99. 

 Encrusting on lamellibranch shells. Two colonies in the collection. 



DIDEMNUM STRANGULATUM sp. nov. 



(PI. XXIX, fig. 28.) 



General characters of the colony. — Flat, incrusting, thin. Largest 

 colony in the collection 4 mm. long by 2 mm. broad ; 5 mm. thick in 

 thickest part, i mm. in thinnest part. Color ashen, zooids showing 

 distinctly through the test. Apparently no systems present ; zooids 

 distributed very uniformly, rather numerous. 



'Bull. Mus. Comp. Zool., xxxv, No. 4, 1899. 



2Norw. N. Atl. Exped., 1876-1879, Zool., Christiania, 1896. 



