154 DISCOPHOR^. Part III. 



Leptobrachia Br., Bull. Ac. Sc. Pet., 1838. 



L. leptopus Br. — Rliizostoma lejitopus Cham, and Ei/senh., Act. 

 Nov. Ac. Leop., Vol. X. PI. 27, fig. 1. — Rhiz. leptocephalus, 

 DeBlainv. (misspelled for leptopus). — Pacific Ocean : Badack 

 Islands (Chamisso and Eysenhardt). 



L. lorifera Ag. — Rliizostoma loriferum Hemp, and Ehr., Akal. des 

 roth. Meeres. — Bed Sea (Hemprich and Elirenberg). 

 3d Family. CassiopeidjE Til. Representatives of two very distinct families 

 have thus far been associated under the generic name of 

 Cassiopea. It becomes, therefore, a question which of these 

 should retain the name apj^lied by Peron and LeSueur to 

 both of them. As Tilesius, in his elaborate monograph of 

 the Cassiopese, Act. Nov. Nat. Cur., Vol. XV., considers Cassi- 

 opea Andromeda (Medusa Andromeda Forsk.) as the type of 

 the genus, and Brandt calls the other type Polyclonia, it 

 seems proper to follow their lead, even though the oldest 

 species known is a Polyclonia, as this species was also included 

 in the genus Cassiopea by Peron and LeSueur. The family 

 of Cassiopeidie differs from all the other Discophorse by the 

 presence of eight genital pouches, alternating with eight arms 

 which form a shield in the centre of the actinostome. The 

 genera differ chiefly in the structure of the arms and the 

 manner in which they are united in the centre of the lower 

 floor. In Cassiopea the arms form a single, eight-rayed rosette, 

 and have numerous lateral dendritic ramifications; each genital 

 pouch has two lateral pouches, corresponding to the tentacular 

 pouches of Cyanea, though there are no marginal tentacles 

 in this genus. In Crossostoma the arms form also a simple 

 rosette, and are branching in the same way, but each arm has 

 a separate tuft of fringes at its base, upon the rosette, and 

 the genital pouches have no lateral or tentacular jiouches. 

 In Stomaster the central rosette is double, in consequence 

 of the special combination of the separate tufts of the basal 

 branches of the arms, but the genital ^^ouches do not divide 

 near the margin of the disk, as in Crossostoma. In Holi- 

 gocladodes the arms are simple, and only crenate along the 

 mai'gin, but they have each a double crescent of dendritic 

 ramifications at the base, and unite in the centre to form 

 a double cross. 



