152 DISCOPHOR^. Part III. 



Mastigias A(j. — Eight arms, arising from a comparatively narrow acti- 

 nostome, with a double row of interlocked marginal folds near 

 their base, and a long, simple, terminal appendage. 

 M. Papua Ag. — Cephea papua Less., Vo}^ Coquille PI. 11, figs. 

 2 and 3). — Cephea papuensis Griffith, in Cuvier's An. King. 

 PI. 3, fig. 3. — Rhizostoma papua Less. — Waigmi Island (Lesson). 



Himantostoma Ag. — Eight slender arms, arising from a wide acti- 

 nostome, ruffled with marginal folds for their whole length, 

 with the excejjtion of their cuspidate termination. Five slight 

 marginal lobes, in each segment, between two of the eight eyes. 

 H. Sueurii Ag. Very pale reddish purple ; margin of the disk 

 and fringes of the arms deeper. — Chhm Sea (W. W. Wood). 



— From a drawing and notes by W. W. Wood, Esq. 

 Catostylus Ag. — Cephea Q. and G. (p. p.). — Rhizostoma Esch. and 



Less. (p. p.). Judging from the position of the eight arms, 

 near the margin of the disk, the centre of the actinostome 

 must be a widely-spread horizontal floor. 

 C. mosaicus Ag. — Cephea mosaica Q. and G., Zool. Uran. PI. 85, 

 fig. 3. — Rhizostoma mosaica Esch. — Rhizostoma mosaica Less. 



— New Holland: Port Jackson (Quoy and Gaimard). 



C. Wilkesii Ag. — Large, new species, fourteen inches in diameter, 

 drawn by Mr. J. Drayton during the U. S. Exploring Expe- 

 dition. It has a general resemblance to C. mosaicus, and 

 the figure before me shows the reticulation of the arms rep- 

 resented by Quoy and Gaimard, to be small bunches of 

 marginal lobes. Slaty colored, rim transparent, with radiating 

 white lines ; surface of the disk crenulate, dotted near the 

 margin. — Illiware Lake (J. Drayton). 

 Rhacopilus Ag. Four large, pointed lobes, in each segment, between 

 two of the eight eyes. Large actinostome, consisting of four 

 pillars, between which are the large openings leading into the 

 four genital pouches, and from which hang eight large arms, 

 covered with numerous folds of the marginal lobes. 



R. cyanolobatus Ag. — Rhizostoma cyanolobata Coxdhouij, Manuscript. 



— Whole surface of the disk granulated, bluish white ; lobes of 

 the margin deep blue; fringes of the arms edged with crimson. 



— Harbor of Rio de Janeiro (Couthouy). From a drawing and 

 notes made by Mr. J. P. Couthouy, during the U. S. Exploring 

 Expedition, under the command of Caj^t. Charles Wilkes. 



