54 TRACK YNEMID^. 



margin of the circular tube (Fig. 72), while at other times it is closely 

 hemmed in on all sides. (Fig. 73.) The base of the tentacles swells 

 out above and below the chymiferous tube, forming a large bulb, in the 

 upper portion of which pigment-cells of a brownish-red color (Fig. 73, m) 

 are loosely scattered, while in the lower portion (Figs. 74, 75, ^/') a 

 dark concentrated pigment-spot is found. The tentacles are hollow, 

 and are surrounded for their whole length by clusters of lasso cells 

 (Fig. 75, I) similar to those of young Tubularian Medusae, such as 

 Coryne and Syndiction. 



The size of this Medusa is about one twentieth of an inch in diameter. 



Found at Nahant, September, Alex. Agassiz. 



Museum diagram No. 16, after Alex. Agassiz. 



^GINOPSIS Br. 



Mginopsis Br. (non J. Miiller). Prod. Mem. Acad. St. Petersburg, p. 222. 1835. 

 ^ginopsis Aga&s. Cont. Nat. Hist. U. S., IV. p. 170. 1862. 

 ^ginopsis Less. Zooph. Acal, p. 304. 1843. 



^ginopsis Laurentii Br. 



jEginopsis Laurentii Br. Mem. Ac. St. Petersb., PI. 6, p. 363. 1838. 



uEginopsis Laurentii Less. Zooph. Acal., p. 304. 1843. 



jEgiriopsis Laurentii Agass. Cont. Nat. Hist. U. S., IV. p. 170. 1862. 



Laurent Bay, Behring's Straits (Mertens). 



Suborder TRACHYNEMID^ A. Agass. 



Forbes, in his Natural History of the British Naked-eyed Medusae, 

 characterized as a family the Circeidte ; at that time only a few other 

 species of this group were known, but so imperfectly described that 

 even at the present day the natural affinities of these Medusge are far 

 from being well ascertained. Gegenbaur, who has studied Medusae 

 which I suppose to be only the young of closely alUed forms, has also 

 separated his young Medusae as a distinct family, under the name of 

 TrachynemidfB. The Dicmcea conica of Lesson may even prove to be 

 the adult of his Trachynema ciliatwn, as it is evident from the draw- 

 ing of Lesson* that he has figured there a Medusa closely allied to 

 Circe Forbes, and perhaps identical with it. A comparison of Trachy- 

 nema ciUahmi (Geg. PI. IX. Fig. 6) with the young specimens of Circe 

 here figured, will show the close affinity of these two Medusae. The 

 family name of Trachynemidae ought therefore yield to that proposed 



* Ann. Scien. Nat., Vol. X. PI. 6, Fig. 3. 



