STOMOTOCA ATRA. 



169 



eter almost immediately above the circular tube, where it curves in 

 slightly, and then bends uniformly towards the abactinal pole ; the 

 upper part is almost hemispherical, being very blunt at the abactinal 

 pole ; the peduncle tapers gradually from the base to the ovaries ; 

 the ovaries are barrel-shaped, extending to the digestive cavity, which 

 is small at the point where the chymiferous tubes empty into it, but 

 gradually bulges out, and passes into the lobes of the actiuostome, 

 where it is three or four times as wide as at the base. Only two of 

 the chymiferous tubes have long tentacles ; between these larger tenta- 

 cles there are a number of small tentacles (in the specimen described 

 about eighty), hardly one sixteenth of an inch long. The ovaries are 

 placed on the abactinal extremity of a long peduncle ; they consist of 

 a double series of folds, occupying the middle third of the peduncle 

 (Fig. 272), and are of a dark-brown color ; below them is placed the 

 digestive cavity, which is very contractile, of a lighter color, and end- 



ing with an actinostome divided into four lips. While swimming, tliese 

 Medusae move slowly, contracting alternately either one or the other of 

 their long tentacles ; when contracted, the tentacle has very much the 

 appearance of the contracted tentacle of a Pleurobrachia ; when floating 

 about motionless, the chymiferous tubes often contract, and this gives 

 to the Medusa the appearance of being deeply lobed (Fig. 273), the 

 intermediate portions of the periphery not seeming to be so highly 

 contractile as that which immediately adjoins the chymiferous tubes. 

 This Medusa was quite common in the Straits of Rosario, W. T., in the 

 beginning of Jvme. I also found specimens of it during the summer, 

 till September, in different parts of the Gulf of Georgia, and in the 

 neighborhood of Port Townsend. 



Gulf of Georgia, W. T. (A. Agassiz). 



Cat. No. 50, Straits of Rosario, W. T., June, 1859, A. Agassiz. Medusa. 



Fig. 271. Stomotoca atra, somewhat magnified ; seen in pi'ofile. 



Fig. 272. Magnified view of genital organs. 



Fig. 273. Stomotoca atra, in a different attitude. 

 NO. II. 22 



