CASSIOPEA XAMACHANA. 195 



and to the canals on the oral disc, the thirteen largest vesicles being one at the axil of 

 the largest branch on each arm and one at each junction of the canals on the oral disc; 

 oral funnels entirely wanting on the oral disc in adult females, but present in immature 

 specimens. 



S2)ecial description. A detailed account of the anatomy of this species will be given 

 in the anatomical portion of this paper. It is intended here to call attention merely to 

 the features that distinguish our species from its nearest allies. Cassiojjea xamachana 

 resembles very closely two medusae that inhabit the Red Sea and Indian Ocean, Cassioftea 

 andromeda Eschscholtz and C. polypoides Keller ('83), but it seems, nevertheless, to be 

 distinct from either. 



Upon comparison with the descriptions of Cassiopea andromeda given by Tilesius 

 ('29), Haeckel ('79), and Vanhoft'en ('88), and with the figures of Tilesius ('29) and 

 Forskal (1776) , C. xamachana appears to differ from this species in the following 

 particulars : The exumbrella is not merely flat, but is concave ; besides the ninety-six white 

 spots on the exumbrella, there is a broad circular band of white more or less connected 

 with all of the marginal spots (Fig. 35), the oral arms are more thickly branched and are 

 longer, exceeding by one half to two fifths the radius of the umbrella, instead of being 

 only one third longer ; moreover the arms have none of the flattened appearance figured 

 by Tilesius and mentioned by Haeckel. 



C. xamachana differs from C. polypoides in having more slender oral arms, with five 

 to seven pairs of branches instead of three, and with fewer very large vesicles, and these 

 apparently not so large and always flattened. The color pattern in the two species is 

 nearly the same, except that in C. xamachana the three white spots on the three velar 

 lobes of each paramere are seldom widely separated from the circuLar band of white. 

 The colors in the pattern, however, differ considerably in the two species. The ground 

 color in C. xamachana is never light brown, but is always much darker, a greenish brown, 

 usually with a distinct shade of blue on the subumbrella. The large oral vesicles are 

 never sky-blue, rose-colored nor white, but are yellowish green, often with a bluish green 

 stripe ; and, while the margins of the oral funnels are deep brown, they are always fringed 

 with the white digitella. 



C. xamachana is easily distinguished from C. ornata Haeckel by the presence of 

 large oral vesicles and by the more extensive branching of the arms ; and it differs from 

 C. mertensii Brandt ('38), C. depressa Haeckel ( ? 80), and C. jricta Vanhoffen ('88), in the 

 number of marginal lobes on the umbrella. C. ndrosia Agassiz and Mayer ('99) differs 

 also in number of marginal lobes and in coloring. Fewkes ('82) has described a medusa 

 from Key West and the Tortugas under the name " Cassiopea frondosa Lamarck," which 

 he regards as identical with Polyclonia frondosa Agassiz. From the description given by 



