﻿OF THE ACALEPH>£ OF NORTH AMERICA. 309 



unable to make out distinctly the nervous ring, which, in other species, follows the cir- 

 cular marginal tube, though I observed a thread accompanying it, which may correspond 

 to the distinct nervous cord noticed in Sarsia, Tiaropsis, and Hippocrene. The marginal 

 fringes are of a light rosy color, and the folds of the mouth either rosy or yellowish. 



From the preceding description, it must be plain that Staurophora belongs to the 

 same family with Thaumantias and Tiaropsis. These genera agree in every respect in 

 their structure, and the differences which occur between them can only be considered as 

 generic. In all, we observe the same narrow central cavity, with a narrow fringed mouth ; 

 in all, chymiferous tubes arise from the central cavity, and communicate with a peripheric 

 circular tube ; in all, we have slender tentacles connected with the margin of the disk, 

 and naked eye-specks at their base. And though such eye-specks are neither mentioned 

 in Brandt's description of Staurophora, nor in the Eudora and Berenice of Peron, and 

 though, in the two latter genera, no chymiferous tubes are described, which, at that time, 

 were not known in any of the Medusas, I have no doubt that both Eudora and Berenice 

 belong also to the same family, Eudora forming the lowest stage in the development 

 of a structure which is more developed in the others. 



The figure of Peron exhibits the small central depression, with four radiating furrows, 

 no doubt the analogues of the mouth of Staurophora, but differing in the deficiency of 

 marginal folds and a prolonged membranous edge, while in Berenice a similar central 

 cross is observed branching towards the margin, as in Forbes's genus Willsia, and, as 

 the figure seems to indicate, provided in its peripheric ramifications with lobules, like 

 those of the Western Staurophora; so that their natural relation cannot be mistaken. If 

 all this be correct, we should at once strike out of our systems Eschscholtz's family 

 Berenicidas, as an artificial group, resting upon imperfect knowledge of the structure of 

 the animals for which it was instituted ; for it can now very properly be combined with 

 that most natural group, first fully understood and characterized by Professor Edward 

 Forbes, the naked-eyed Discophorous Medusae. A comparison of an ideal vertical section 

 of Staurophora (Plate VIII. Fig. 12) with those of the genera Hippocrene, Sarsia, and 

 Tiaropsis (Fig. 3, 6, and 11) will satisfy the most skeptical of the close relation of these 

 genera, and justify my assertion, that Staurophora is truly a member of the family of 

 naked-eyed Medusas. The letters indicating the different organs in this section corre- 

 spond precisely to those indicating the homologous parts in the other genera ; and need, 

 therefore, no further explanation. 



42 



