Chap. VI. TABULAR VIEW. I57 



Besides the two species of Forskfil, Peron and LeSueur 

 refer three others to the genus Cephea : 1, C. polychroma 

 Pa: and LeS. ; 2, C. ocellata Per. and LeS. ; and 3, C. fusca 

 Per. and LeS. An attentive comparison of the descriptions 

 of these species shoAvs the first to be a Cotylorhiza, the 

 Cassiopea borbonica Delle Ch., or Rhizostoma borbonica Esch.; 

 the second a genuine Cephea, aUied to C. octostyla ; and 

 the third a Polyrhiza, allied to P. Cephea. Lamarck has 

 added nothing to this genus, but simply copied Peron and 

 LeSueur. The Cephea capensis Q. and G., Zool. Uran., p. 568, 

 is, very likely, a genuine Rhizostoma, while the Cephea mosaica 

 Q. and G. (Rhizostoma mosaica Esch.) constitutes a distinct 

 genus, which I have called Catostylus. To these must be 

 added the following new genera. 

 Diplopilus Ag. In the figure of Polyrhiza Cephea, published by 

 Forskal, the summit of the umbrella is depressed, and evi- 

 dently injured. In the centre of the depression there appear 

 singular bodies which could not be understood by reference 

 to any known Medusa. Among the drawings of Discophorae 

 made during the U. S. Exploring Expedition bj' J. P. Cou- 

 thouy, Esq., there is, however, one representing an Acaleph 

 of the same fiimily, which explains this puzzle. From the 

 centre of the umbrella arises a cupola, occupying about one 

 third of the whole diameter, made up of large conical tuber- 

 cles, and standing out prominently from the upper part of 

 the disk. This dome corresponds, in extent, to the central 

 cavity, and is the part sunk in the figure of Forskal. From 

 its outline arise eight simple radiating tubes, which reach 

 the base of the eight eyes. In each of the segments thus 

 circumscribed arise ten or twelve simple chymiferous tubes, 

 which anastomose in arches at some distance, and then, 

 doubling their number, radiate in a straight course for twice 

 the distance, towards the margin, where they anastomose 

 again, and, increasing further in number, reach the margin 

 in a network of anastomoses. The margin of the disk is 

 divided, in each segment, into eight pointed lobes. The 

 actinostome consists of four broad arms, with numerous 

 fringes and many slender tentacles along their whole margin. 

 Each flat arm is broadly furcate at its extremity. 



