■200 CTEXOPIIOR.E. Part II. 



Curio?!. X. PI. ol. Fit/. ?)), the typo of Esch.^clioltz'.s genus Ilapalia. aftenvaiils called 

 Poh-])tera by Lesson.' Fully to appreciate the peculiarity of the form of the 

 Euramphanihv, it must be borne in mind that the lobe-like prolongations of their 

 most prominent spheromeres trend in the direction of the ca?liac chamoter on the 

 actinal side of the body, as in the Mnemiid;v proper, while the appendages on the 

 abactinal side rise as keels from the broad side of the animal and j^roject in the 

 direction of the diactvliac diameter, like the most prominent spheromeres of the 

 ^lertensida^ except that in the family of Euramphtvidiu they are still more promi- 

 nent and assume the shape of elongated horns. Iir consequence of this arrangement, 

 the appendages of the actinal and those of the abactinal side of the spherosome 

 stand crosswise. 



The B0LIXID.E constitute a second family among the CtenophoriV Lobata\, including 

 part of Eschseholtz's Mnemiida^ and of Gegenljaur's Calymnida^, part of Lesson's 

 tribe of CalUanira\. his Leucothoea^, and jjart of his Calynnnea\ Lesson's attempt 

 to subdivide the Ctenophora^ into minor groups was a lailure, the tribes he adopted 

 bemg entirely artificial. The characters he assigns to the Callianira' exist oidy 

 in a few of them : for neither Mnenua nor Bolina has prominent ribs, the rows 

 of locomotive iiap2)ers being nearly on a level with the surfocc of the spherosome : 

 while Leucothea, which he separates, as a tribe, from Bolina, is closely allied to 

 it ; and Chiaja, which he refers to the Callianira^, is identical with Eucharis multi- 

 cornis. — and yet Lesson places Eucharis in another tribe. Under such cuxnimstances, 

 the first step we have to take in order to ascertain the general relations of all 

 these Acalephs is to compare them more minutely with one another. I shall, of 

 course, take as my standard the representative of the whole type which I know 

 best, — the Bolma alata of the American coast of the Northern Atlantic. The 

 characteristic form of this Acaleph is determined by the prominence of the anterior 

 and posterior spheromeres over the lateral pau-s, and the equable convergence of the 

 eight spheromeres towaixls the al)actinal pole, Avhich gives a rounded form to that 

 side of the spherosome. while the anterior and posterior spheromeres extend bej'ond 

 the actinal pole, and the shape of two lobes, more or less expanded in tlifierent 

 genera. Ijut always closely connected with the actinal region. Upon the sides arise 

 two auricles in the prolongation of the lateral rows of locomotive liappers. 



Mnemia norvegica jSars and Bolina septeutrionalis Jlc/i. have exactly the same 

 form, and agree so full}' iu the details of their structiu'e with Bolina alata, that I 



^ Lessoa's name cannot be retained, not only tem der Acalephen," Escliseholtz does not mention 



because it is preoccupied, but also because it is of this genus, not even as synonvm, but refers the 



later date than that proposed l)y Esehscholtz (Isis, species upon which it was founded to the geuus 



1820, p. 742) for the same Acaleph. In his '• Sys- Mnemia as 31. Chamissonis. 



