BOLINA ALATA. 15 



Bolina alata Agass. 



Bolina alata Agass. Mem. Am. Acad., Vol. IV. I't. 2. p. 349, PLs. G, 7, 8. 1819. 



Bolina alala Agass. Coiitrib. Nat. Hist. U. S., Vol. III. i)p. 249, 289. 



Alri/nOi' renniciitaris Gori.D (^non Raiijr)- Invortch. of Ma.ss., p. 349. 1841. 



Bolina alala SmiPii, Mar. Iiiv. Grand Manqii, p. 11. 18.53. 



Bolina alala Packd. A List of Animals dredgud nuar ('arlbou Island, Can. Nat. & Geol. 1863. 



It is quite remarkal)le that there should Ije no mention made by 

 Fabricias of a single Ctenophore whieh may be identified ■with any 

 species of the genus Bolina, There is hardly a more common Medusa 

 than the Bolina alata of our coast ; and the occurrence of so many of 

 our species of Ctenophoraj on the coast of Greenland makes the ab- 

 sence of Bolina the more striking, and quite interesting in a geograph- 

 ical point of view, as we should thus have among Acalephs a case of 

 geographical distrilmtion analogous to that of Echmarachnius, which 

 does not extend farther north than Labrador. 



To the description of the adult given by Professor Agassiz I have 

 nothing of importance to add, with the exception that the chymiferous 

 tubes which run along the edge of the lateral loljes, when seen from 

 the narrow side, should unite, and Tthus complete the circuit (Fig- 16), 

 instead of stopping short at a little distance apart, as they have been 

 represented by him. This connection takes place at an early period of 

 the development. (See Fig. 8.) 



The compression of the spherosome of Bolina and of Pleurobrachia 

 is in diflerent planes, otherwise it would be exceedingly difficult to 

 distinguish a very young Pleurobrachia from a young Bolina. In the 

 young Bolina, as has been shown alread}' by McCra- 

 dy, we find long tentacles; so that the younger stages 

 of this Medusa are so unlike the adult, that it would 

 be the most natural error to commit, to consider it 

 the young of Pleurobrachia. The accompanying fig- 

 ures (1-3) are taken hnmediately after the escape of 

 the young from the egg. It will be noticed, when compared to Pleuro- 

 brachia, that besides the position of the tentacular organ, the outline of 

 the spherosome is somewhat dilTerent, and that the ambulacra are quite 

 narrow. The digestive cavity also fills a comparatively small space. 

 (Fig. 2.) The extreme tenuity of the tubes soon becomes a character 

 by which the young Bolina is Jit once distinguished from the young 

 Pleurobrachia, as well as its ellipsoid shape, which greatly increases 



In all tlu> yonnr; C'lcnopliorir tlic Inllowinj; li'ttcrin;^ lias ]irru adiipti'd : r/, dijjcstivc cavity; 

 a, anal i-osuttL' ; /, tentacle ; <•, long andmlacral tidic (longitudinal anilndacra) ; c', short andjidacral 

 tulx- (lateral andiulacra) ; c eye speck ; /', fnnnel ; o, anilndacral cavity; /, lateral tnlics. c' is the 

 longest tnbc at fii-st. and <■ the shorter : n, lobes of s|iherosonie ; the names are taken from the adult. 



Fig. 1. Young Bolina, seen from the narrow side. 



