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PROCEEDINGS OP THE 



[April, 1857. 



the individuals appended to it. I therefore defer the description 

 of this species, which may perhaps properly be called D. pusilla, 

 to a future time. 



These two specimens were taken in summer. 



DIPHYES PUSILLA, nov. spec. 



This small species in form is intermediate between Eschscholtz's 

 D. angustata and Kolliker's B. Sieboldii. The greater swim-bell 

 is relatively greater in height than in D. angustata while the 

 smaller bell projects much less downwards than in D. Sieboldii. 



II. PHYSOPHORID.E. 



In this group the basal medusa, has its disk reduced to a 

 small air vesicle, its digestive trunk usually long in proportion 

 and bearing numerous appendages, of which the uppermost are 

 the swim-bells which here reach their highest numerical develop- 

 ment. Similarly numerous are the bracts which overlie the 

 digestive trunks, and which in this group are still less like the 

 bells of ordinary medusas, than they are among Diphyidae, while 

 in the next group they are entirely wanting. The sexual medusae 

 are usually arranged in clusters as in Physalia, and appear to be 

 more nearly allied in form to free ordinary Endostomata, than the 

 sexual medusas either of Diphyidae or Physalidae. 



I have never seen any species referable to this group ; Charles- 

 ton Harbor, so far as my observations yet extend, does not afford 

 one. Even one or two injured transparent bells not here described, 

 though evidently detached from some Siphonophorous community, 

 appeared to me rather referable to Diphyidae than Physophoridee, 

 so far as I am acquainted with the group from the writings and 

 illustrations of others. 



III. PHYSALIDAE. 



The communities of medusae in this group, have the basal me- 

 dusa reduced to a mere cyst containing an air-vessel surrounded 

 by a cavity whose walls (perhaps corresponding to the upper por- 

 tion of the cavity of the digestive trunk in Eudoxia,) are either 

 prolonged in a single tubular stem (Rhizophysa) or metamorphosed 

 by gemmation into a branched cartilaginous structure on the under 

 side of an enormously developed air-vessel (Physalia and An- 

 gela ? ). Its sub-divisions in this later case are tubular, and 

 their canals communicate with the cavity between the outer and 



