98 HYDROZOA. 



Diphyes attain, when fully extended, a length of 

 several inches, their coenosarc giving support to at 

 least fifty distinct polypites. Of the great beauty of 

 these, and other oceanic Hydrozoa, no description 

 can adequately treat. So transparent, in many 

 cases, is the delicate coenosarc, that its course upon 

 distant inspection is revealed only by the bright 

 tints of some of its appendages. A touch is often 

 sufficient to separate it from the nectocalyces, 

 which, from their size and firm consistence, con- 

 stitute the most conspicuous portions of the or- 

 ganism. Hence the origin of the generic name, 

 Diphyes, devised by Cuvier, who regarded the two 

 swimming organs as distinct animals, imperfectly 

 united with one another. 



An unbranched, filiform, coenosarc occurs in all 

 Calycoplioridce, In Hippopodius its proximal 

 extremity lolds inwards to form a loop, so that the 

 true position of the nectocalyces is thereby some- 

 what confused. 



Of the many appendages to the coenosarc by far 

 the most remarkable are those just mentioned. In 

 accordance with the relative number, structure, 

 and arrangement of these organs, the few genera 

 of the order hitherto carefully examined may 

 readily be identified and separated from one ano- 

 ther ; as shown in the accompanying table. 



Artificial Areaxgemext of CALYCOPHOEID.E. 



Nectocalyces two in number ..... 2 



Nectocalyces numerons, similar ..... 4 



A single, proximal, spheroidal, nectocalyx . SphcRroncct'i'. 



j" Nectocalyces unlike in size and form .... 3 



\_ Nectocalyces similar ..... Praya. 



f Proximal nectocalyx equal to, or larger than, 



•| the distal one Diphi/rs. 



(^Proximal nectocalyx shorter than the distal Ahyla. 



