118 POLYORCIIID.E. 



of the circular tube, c. The bell widens very rapidly towards the lower 

 floor, and is perfectly transparent ; the ovaries, as well as the tentacles 

 and the proboscis, are colorless ; the diameter of the bell is nearly two 

 inches, and the polar diameter about half an inch ; the proboscis is usu- 

 ally carried as in Fig. 173, and, as the digestive cavity is capable of but 

 slight contraction, it bears usually the proportions of that figure to the 

 diameter of the bell. Found in Buzzard's Bay during September. 

 Buzzard's Bay, Naushon (A. Agassiz). 



Eutima pyramidalis Agass. 



Etilimu pyramiikilis AaXss. Cont. Nat. Hist. U. S., IV. p. 3G3. 1862. 



The spherosome is hemispherical, and more heavy than in either 

 Eutima llmjnda or E. mira ; the proboscis is shorter, and tapers rap- 

 idly ; the tentacles are short ; the oral leaflets are rounded and sepa- 

 rated by an indentation from one another, the edge of the leaflets being 

 finely scalloped ; the digestive cavity is short. 



Florida, Key West (L. Agassiz). 



Family POLYORCHIDiE A. Agass. 



Poli/orchiilce A. Agass. ; in Agassiz's Cont. Nat. Hist. U. S., IV. p. 349. 1862. 



This family is characterized by the peculiar structure of the chymif- 

 erous tubes, which, sending off diverticula at right angles to the main 

 tube, give these Medusa? a very peculiar aspect. With the exception 

 of Polyorchis, we know of only one other genus, Olindias Fr. Miill., 

 which has the same structure of the chymiferous tubes. Miiller, at the 

 close of his description of O. sambaquiensis, says it is characteristic of 

 the uncertainty which still exists in the classification of Acalephoe, that 

 the attempt to assign to this Medusa its position in the systems of Esch- 

 scholtz, Forbes, or Liitken, places them in families with which they have 

 no affinities, and we cannot even assign them to any of the families of 

 Gegenbaur ; the only genus to which it seems to liave any relation is 

 Melicertum Oken. This suggestion of Miiller, as to the affinities of his 

 genus Olindias, is fully borne out by the examination of the Mdlcerhim 

 peniciUahon of Eschscholtz, which has, like it, peculiar chymiferous 

 tubes, and also the discovery of Gonionemus, a genus having the gen- 

 eral appearance of Olindias without the ramifying chymiferous tubes. 

 Gonionemus shows us the close relation that exists between these 

 genera and Melicertum, although the dilTerences existing between 

 Olindias and Polyorchis on one side, and Gonionemus and Melicertum 

 on the other, are such as to form very natural families. 



