348 
REVIEWS. 
names of the other orders having been mentioned above) and in¬ 
clude— 
a. the Discophorce of Kolliker, 
ft. the Charyftdeidce of Gregenbaur, 
c. the Lucernariadce of Johnston, and 
d. the family AEginidce. 
The question, therefore, as to the systematic value of the struc¬ 
tural differences between the Phanerocarpce and Cryptocarpce resolves 
itself into a discussion concerning the position of the two doubtful 
families, Charyftdeidce and JEginidce. To place this in a stronger 
light let us remove these families, provisionally, from the order 
Discophorce, Esch., and, this being done, contrast its primary sections 
with one another. 
In the Cryptocarpce , thus limited, the margin of the swimming” 
bell is entire, and always furnished with a ‘ veil.’ The radiating 
canals, which never anastomose, open into a circular marginal vessel. 
The reproductive organs are situate, either within the walls of the 
digestive appendage (polypite) depending from the roof of the bell, or 
along the course of its radiating vessels; never on the floor of the 
central cavity whence these originate. Their contents, when 
developed, escape directly into the surrounding medium. The 
naked marginal bodies, sessile at the bases of the tentacles, or 
placed (rarely on stalks) # in the interspaces between them, have no 
communication with the canal system. 
In the Phanerocarpce the margin of the disc is always indented, 
and a veil is often absent. A veil-like structure, however, exists 
in the common jelly-fish (Aurelia), so that the character selected 
by Gregenbaur to distinguish more accurately this group from 
the Cryptocarpce is of no avail. Still less can we seek to sepa¬ 
rate the two divisions by referring to the more depressed disc, 
numerous radiating canals, and comparatively short oral apparatus,! 
characteristic of most (though not all) Phanerocarpce. For some of 
the Cryptocarpce J will be found to rival them in each of these 
particulars. But all Phanerocarpce differ strikingly from the Crypto¬ 
carpce in the structural relations both of their reproductive organs 
and marginal bodies. The former are developed within sac-like 
depressions, or processes, of the floor of the central cavity, into which 
the ova or spermatozoa are discharged. The marginal bodies, which 
never present themselves at the bases of the tentacles, are placed at 
the free extremities of hollow stalks, each containing a coecal pro¬ 
longation of the neighbouring radial vessel. Beyond this process lies 
* This is, however, the case with the Tiaropsis diademuta of Agassiz, the 
marginal bodies of which are described at page 308 of the present volume. 
f The structure of this apparatus, with its four stout pillar-like angles, radia¬ 
ting proximately along the floor of the common cavity, is, however, as Professor 
Agassiz here reminds us, a true distinctive feature of the higher Medusce. 
t For example, certain JEquoridce. See the account by Forbes of a large 
British species of this genus in Zool. Proc., 1851. 
