﻿OF THE ACALEPHvE OF NORTH AMERICA. 301 



the lower surface numerous arms, (fringed folds of the margin of the mouth,) which 

 form two stripes or ribbons alternating with each other in such a way as to constitute 

 a cross ; — the margin of the disk furnisbed with numerous tentacles. 



This new genus is there represented as differing from Eudora by the presence of 

 suckers and marginal tentacles ; and from Berenice, which possesses long marginal tenta- 

 cles, in the foliaceous arms arranged in the shape of a cross. In the possession of 

 arms it shows a resemblance to Medusa campanulata [Melicertum~\. But this latter 

 genus has thread-like arms, and the tentacles around the margin are in several rows, 

 of unequal length. The specific description there given, and the figures reproduced 

 from Mertens's drawings, under the name of Staurophora Mertensii, afford some further 

 information upon this remarkable animal. 



It is described as being slightly convex, clear as water, and perfectly transparent. 

 Each arm of the cross, which is tinged more or less deeply with blue, possesses on each 

 side from seventeen to twenty-one arms, each of which has a lanceolate or a linear-lan- 

 ceolate and undulating or fringed margin and acute terminations. The arms hang down- 

 wards with their free margin, but remain united at the base by a narrow continuous 

 membrane extending for their whole length, from which issue a few additional small 

 processes or appendages. 



Brandt says that it may be possible, as Mertens maintains, for these arms to absorb 

 nourishing substances, in a manner analogous to that of the Rhizostomata, in which the 

 arms, however, have a different structure. The fact that the four peripheric extremities 

 of the arms of this cross terminate in a distinct marginal vessel would sustain this view. 

 Numerous tentacles, by no means remarkable for their length, are in connection with this 

 marginal vessel. Within the margin to which the tentacles are attached, there is a 

 prominent seam. 



The movements of this animal are very characteristic. It can, not only change its 

 form and place after the fashion of other Medusae, but also contract in such a manner as 

 to assume the form of a regular four-rayed star, thus somewhat resembling an Asterias ; 

 this form it assumes very frequently. 



The first specimens of this Medusa were collected in Norfolk Sound ; it was ob- 

 served afterwards in the ocean of Oonalaska, and finally, on the 20th of August, 

 1827, it was seen from the Senjevin on her trip between Sitka and the Aleutian Islands. 



This is all we know at present about this remarkable form of Medusa, as nobody has 

 ever seen any animal of that genus before or since. Its natural position among Dis- 

 cophorous Medusae is rather doubtful. Brandt places it, with doubt, in that family which 



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