150 DISCOPHORiE. Part III. 



marginal tentacles, and pedunculated clusters of lasso-cells. 

 The body consists of four spheromeres, and has eight mar- 

 ginal eyes, four in the prolongation of the ambulacral chy- 

 miferous tubes, and four in the prolongation of the medial 

 chymiferous tube of the genital pouches. To the sides of 

 each of these pouches there are radiating chymiferous tubes 

 without eyes. For one half of their extent, near the margin, 

 the chymiferous tubes form a close network of anastomoses, 

 closest near the margin, and rather loose between the main 

 branches of the system. Milne-Edwards has published, from 

 injections of the Ehizostoma Cuvieri, the only accurate illus- 

 trations existing of these ramifications. 

 Rhizostoma Cuv. 1817. — Cephea Lmk. — Holigoclonia Br. — Claustra 

 Less. (p. p.) 



As now circumscribed, the genus Rhizostoma embraces only 

 those species in which the actinostome is divided into eight 

 arms, the marginal lobes of which are clustered into two 

 distinct bunches, one smaller, near the base of the arms, 

 another larger, extending to near their extremity. The arms 

 terminate in a simple point. 



R. Corona Esch. — Medusa Corona Forslc. — Cephea Corona Lmk. 

 — Rhizostoma Corona Esch. — Rhizostoma Forskfdii Per. and 

 LeS. — Rhizostoma Forskalii Less. — Red Sea (Forskal). This, 

 and the following species, are very imperfectly known. 



R. tetrastylum Less. — Medusa tetrastyla Forsk. — Rhizostoma Cuvi- 

 eri Ehrenb. — Red Sea: Sues (Forskal), (Hemprich and Ehren- 

 berg). 



R. Cuvierii Per. and LcS. — Gosse, Tenby PI. 1. — Rhizostoma Cu- 

 vieri Esch. (p. p.). — Rhizostoma vmdulata Flem. — Cephea 

 Rhizostoma Link. — Rhizostoma pulmo Forbes. — Atlaniic Ocean: 

 English coast (Forbes) ; English Cliannel (Peron and LeSueur). 



R. pulmo Ag. — nvevuwv Arist. — Urticaj quinta species Rond. — 

 Medusa pulmo L. — Rhizostoma Aldovandi Per. and LeS. — Ce- 

 phea Aldrovandi Lmk. — Cephea Rhizostoma Eysenh. (Act. nov. 

 Nat. Cur. Vol. X. PL 34. Excellent anatomical description). — 

 Rhizostoma Cuvierii Esch. (p. p.). — Rhizostoma Cuvierii Milne- 

 Edwards (Voyage en Sicile, PI. IX. ; copied in Cuvier's Regn. 

 Animal, Pis. 49 and 50, here for the first time represented 

 as fully injected). — Mediterranean: Nice (Peron and LeSueur). 



