Chap. III. GENUS BOLINA. 249 



SECTION II. 



THE GENUS BOLINA AND ITS SPECIES; WITH REMARKS UN ALLIED GENERA. 



The genus Bolina was first described by Mertens, from two species observed in 

 the Pacific and in Behring Strait.^ It is considered as differing from other genera 

 of CtenophorjB by the great development of the mantle lobes, and by the circum- 

 stance of its eight rows of locomotive flappers not extending beyond the body 

 itself; and though this characteristic is not strictly correct in as for as I shall 

 be able to show that the ambulacral rows are not strictly circumscribed within 

 their apparent limits, the genus itself is a very natural group, which ought to be 

 generally acknowledged. I have already stated (page 201), that the genus Bolina 

 differs so for from Mnemia as to constitute a distinct family, the lobes of the 

 spherosome being only actinal prolongations of the anterior and posterior sphero- 

 meres, while in Mnemia and Alcinoe they arise as lateral folds between the lateral 

 and the anterior and posterior spheromeres. I have also pointed out generic difler- 

 ences l^etween Bolina elegans Ileii. and Bolina septentrionalis 3Iert., which will require 

 their separation; but I would retain the name of Bolina for the type to which 

 B. septentrionalis Mcrt., our B. alata, and Sars's Mnemia norvegica belong. It is 

 difficult to give a correct idea of the form of these animals, as they assume most 

 diversified aspects in their various movements, and in the different attitudes in 

 which they have to be considered. Having had ample opportunities repeatedly and 

 for a longer time to examine a new species of this genus which I have kept 

 alive, at intervals, 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 fomily, 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 Bed- 

 ford, 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. I now know 

 that it may be found through the whole summer, not only along the coast of 

 Massachusetts and Maine, but even as far north as Laljrador. Dr. A. A. Gould, 

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



^ This genus is cliaractevized in a remarkable ences, in St. Petersburg, in the second volume of 



paper by Mertens on Beroid Medusa^ published in the sixth series, 1833. The species described are 



the Transactions of the Imperial Academy of Sci- chiefly from tlie Pacific. 

 VOL. III. 32 



