494 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 45. 



each traus\erse vessel; the series a little to the right side of the 

 median line. The median line itself marked by a narrow strip of the 

 branchial membrane in which there are no stigmata (fig. iOd.l.). Bran- 

 chial membrane with neither longitudinal folds nor vessels, but 

 with prominent transverse vessels or folds, the edges of which are 

 armed with numerous long, strong processes each conical in shape 

 with its free apex usually curved or hooked, about 10 or 12 of these 

 vessels in each sac. Stigmata long and closely and definitely coiled, 

 there being in general two rows of spirals in the interval between 

 each two transverse vessels; about three or four turns in each spiral; 

 usually four somewhat irregular vessels radiating quadrant-wise 

 from the center of each spiral (figs. 40, 41). 



Alimentary system. — On the left side, the stomach and first half 

 of the intestine forming a close loop reaching across the posterior 

 end of the body; the second or rectal half of the intestine forming 

 nearly a right angle with the first part, and runnmg forward along 

 the dorsal side of the body (fig. 37). Stomach but little thicker than 

 the intestine, and not definitely set off from it; wall smooth. Anus 

 with a somewhat toothed border (fig. 38). 



Rejjroductive system. — In the intestinal loop, the ovary a rather 

 regular mass situated centrally (ov. fig. 38), with the testes disposed 

 in the form of a fringe around this, the whole when fully developed 

 spreading sometimes over the outer surface, sometimes over the 

 inner surface, and sometimes over both surfaces of the intestmal 

 loop. Gonoduct large, running parallel with the intestine and in 

 close contact with it, ov. d., in some individuals to the outside, in 

 some to the inside of the rectum. 



The genus Agnesia was founded by Michaelsen (1898) for an 

 ascidian rather closely related to Corella, coming from Tierra del 

 Fuego. A much fuller description of the animal was published by 

 the same author in 1900. Up to the present time no other species 

 of the genug has come to light, and it is an interesting circumstance 

 that the second one should come from a latitude in the northern 

 hemisphere almost the counterpart of that in the southern from 

 which the first species comes (southern Tierra del Fuego, the home 

 of A. glaciata, the original species, is in about 53° south, while the 

 specimens of A. heringia come from 54° to 57° north in Bering Sea). 



On the whole, too, it seems that the two are very much alike. 

 It is true that A. glaciata is described as being without a peduncle, 

 and since the present species is pedunculated this difference of 

 itself would seem to separate the two generically almost, to say 

 nothing about specifically. However, Michaelsen had only two 

 specimens, one a small one, and the other, seemingly full-grown, was 

 badly injured. This fact, along with the fact that many of the speci- 

 mens at hand seem to be devoid of the peduncle makes me suspect 

 that, were a large number of individuals of the South American 



