Chap. II. GENERIC AND SPECIFIC CHARACTERS. 83 



to be, or Avhether part of these differences are the result of imperfect observations, 

 future researches alone can decide, and I trust European zoologists Avill soon make 

 a renewed comparison of their species with that of our coast. 



From an examination of alcoholic specimens of the European species, which I 

 have obtained since the above was written, I ascertain that the veil not only 

 exists, but is as well developed as in the American species. I cannot, however, 

 detect the lobules between the tentacles, nor are sockets around the base to be 

 distinguished ; but this does not yet prove their absence, as the margin of the 

 disk is highly contractile. For the opportunity of examining these specimens, I 

 am indebted to Thomas J. Moore, Esq., of the Free Public Museum in Liverpool, 

 who has lately sent to me great numbers of interesting marine animals from the 

 coast of England, many of which reached me alive, thanks to the care bestowed 

 upon them Ijy my friend. Captain James Anderson, during their passage across 

 the Atlantic. 



Mertens has also observed a broad and conspicuous veil in a species from Kamt- 

 schatka, which he has figured under the name of Aurelia limbata, and upon this 

 character Brandt has founded the genus Diplocraspedon ; but unless other generic 

 differences are pointed out, this species must be united with the Aurelia3 of Eu- 

 rope and North America, which do not differ in that respect from one another. 



There are almost insuperable difficulties to the compai'ative studies of the species 

 of Acalephs. Thus far no attempts have been made to collect and preserve them 

 for repeated study, and the figures and descriptions, which have been published, 

 are generally so imperfect, that it is utterly impossible, from their comparison, to 

 arrive at any kind of satisfactory result as to the true character of the species. 

 Notwithstanding the discrepancies already pointed out between the Aurelia of our 

 coast and that of Europe, it may still be questionable whether they differ spe- 

 cifically, if the differences which are apparent by a comparison of the figures of the 

 European species with ours should prove to be the result of imperfect observa- 

 tion. Fabricius, at least, considers the Medusa, observed by him on the coast of 

 Greenland, the same as the European species. It should, however, be remembered, 

 that this identification was made at a time when it was not suspected that there 

 could exist specific differences between animals resembling one another very closely ; 

 and Fabricius himself described a Starfish, also found on the coast of Greenland, 

 as identical with the Asterias rubens of Europe, though a direct comparison of 

 American and European sjoecimens has satisfied me that they are C[uite distinct, 

 as are also many other animals supposed for a long time to be common to the 

 two sides of the Atlantic. I am, therefore, inclined to believe that our Aurelia 

 will prove different, and that some of the differences between them, pointed out 

 above, may be specific. I have, on that account, adopted for our species the 



