CffiLENTEKATA. 25 



Order IV. HAPLOMOEPHA. 



CRYPTOCARPJE. CRASPEDOTA. HYDROPHORA. MONOPSEA. 

 TRACHYMEDUS^E. 



No hydriform trophosome ; medusae developing directly from 

 the ovum. 



These are the true Medusae ; but at present the order can only 

 be regarded as provisional. The embryo, so far as is known, is 

 directly developed from the parent without passing through any 

 intermediate form as in the medusiform gonophore. Both seem 

 able to produce independent forms like themselves by budding. 

 Many naked-eyed Medusas (Gymnophthalniata of Forbes) are now 

 known to be the free gonophores of the Gymnoblastea and the 

 Calyptoblastea. Some are very minute, others attain the size of a 

 walnut. 



The Acalephae of Cuvier comprised this order, Discophora, 

 except Lucernaria, Siphonophora, and Ctenophora. 



Trachynemida, Cunina. Liriope. 



Trachynema = Circe. -^Sgineta. Carmarina. 

 Ehopalonema. Polyxenia. 

 Aglaura. Ckarybckridtf. 



Geryonlid. Charybdsea. 

 Geryonia. 



Order V. HYDEOCOEALLIN.E. 



Polypary calcareous, sometimes divided into compartments by 

 transverse partitions. Mouth of the polypites with or without 

 tentacles. 



The coenosarc is made up of a "network of anastomosing 

 canals," and its outer layer is provided with thread-cells. The 

 zooids are of two kinds ; the smaller and more numerous have no 

 mouth and no stomach-cells. Eeproduction is by means of 

 gonophores. 



The Milleporidae, " in the general form of their zooids, seem 

 allied to the gymnoblastic hydroids, whereas the presence of 

 distinct gonaugia in the Stylasteridae seems to ally the latter to 

 the calyptoblastic group " (Moseley}. 



