OF THE ACALEPHiE OF NORTH AMERICA. 319 



Altliougli I have kept Beroe alive for a month during spring, I have never seen 

 in any of them any thing like ovaries and spermaries, and have not even succeeded in 

 ascertaining in what part of the body the organs of reproduction are developed. And 

 I must confess that the descriptions published by various authors respecting the sexual 

 apparatus of Beroe have not yet satisfied nic of the correctness of their statements. 



BOL IN A. 



The genus Bolina was established in 1833 by Mertens, from two s|)eci(;s, oik; of 

 which was observed in the Pacific, and the other in Behring's Straits. The genus is 

 characterized in a remarkable paper on Beroid Meduste, published in the Transactions of 

 the Imperial Academy of Sciences, in St. Petersburg, in the second volume of the sixth 

 series. It is considered as distinguished from other genera of that family by the great 

 development of the mantle lobes, and by the circumstance of its eight rows of locomotive 

 fringes not extending beyond the body itself; and though this characteristic is not strict- 

 ly correct, in as for as I shall be able to show that the anihuiacral rows are not strictly 

 circumscribed within their apparent limits, the genus itself is a very natural group, 

 which ought to be generally acknowledged. It is difficult to give a correct idea even 

 of the forms of these animals, as they assume constantly different aspects in their 

 various movements, and in the different attitudes in which they must be considered. 

 Having had an opportunity to examine at repeated intervals, and for a longer time, a 

 new species of that genus, which I have kept alive for months, I shall attempt to give 

 a more complete idea of its remarkable structure, which may throw some new light 

 upon the organization of the whole family, and also upon the natural relations which 

 exist between its different genera. I saw this new animal for the first time, with Mrs. 

 Arnold, of New Bedford, who had preserved it alive for my examination, in December, 

 1848. I myself afterwards found large numbers of specimens, during the months of March 

 and April, and even as late as June, in various parts of Boston Bay. Dr. A. A. Gould, 

 however, had already noticed this species as an inhabitant of the shores of Massachusetts, 

 in his Report on the Invertebrated Animals of that State, where he considers it, however, 

 as identical with the Alcinoe vermicularis of Europe. But a close examination has 

 satisfied me that it is neither identical with that species, nor even belongs to the 

 genus Alcinoe, but constitutes the first Atlantic representative of the genus Bolina.* 



* It is a remarkable circumstance, that the Atlantic shores of America should furnish, in lower latitudes, 

 a species of that genus so similar to that which occurs in Behring's Straits ; but this is only one of the 



