Chap. II. CTENOPHOR^E LOBAT.E. I99 



that tliorefore its young may be widely different from the adult, and is not 

 likely to resemble the young of other genera, considei-ing the tA'pical peculiarities 

 of Cestuni ; when it is further rememl^ered that the tentacular apparatus of Sicy- 

 osoma trends in the direction of the mouth, as in Cestum, — this supposition will 

 appear more probable than that of Gegenbanr, who regards it as an adult form 

 of a very low organization. 



SECTION IV. 



THE NATURAL FAMILIES ()F THE CTENOPHOR.E LOBAT.Io. 



Eschscholtz was the first to perceive the affinities which unite these Acalcplis 

 into one natural group, to which he gave the name of Beroidae Lobatao in the 

 account of his investigations published in the Isis for 1825. Four years later, he 

 changed that name to Mnemiida", in his "Sj'stem der Acalephen;" but, as we have 

 already seen, the Ctenophoras Lobatte constitute a natural sub-order, and not simply 

 a fiimily. Lesson, on the other hand, regarding the Avhole type of Ctenophor* 

 as one fomily, subdivided it into eight tribes, three of which, the Leucothoea', the 

 Seuroea\ and the Calymme*, belong to the Ctenophoraj Lol^ata?, while his Calli- 

 anira3 embrace Cydippidas as well as genuine Lobatte. Gegenbaur unites all these 

 Acalephs into one famil}-, called l)y him Calymni(h\?. It is not difficult, however, 

 to trace different patterns among them. In the first place, I would call attention 

 to the very peculiar form of the genus described by Gegenbaur under the name 

 of Eurampha^a. It differs from all other Ctenophorai by the remarkable promi- 

 nence of the actinal diameter, which gives this type a very elongated appearance, 

 strikingly contrasting with the prominence of the coeliac diameter in others. Again, 

 the compression of the sides, combined with the sudden dilatation of the anterior 

 and posterior spheromeres into broad lobes projecting from the actinal part of the 

 narrow sides of the body, and the ec^ually prominent projection of the abactinal 

 part of the broad sides of the body, extending sideways much beyond the abactinal 

 pole, give this Acaleph a very unusual appearance, and show it to be the type of 

 a distinct family, for which I propose the name of Euramph^eid^e. Besides the genus 

 Eurampha^a, I am inclined to refer to it another Acaleph, thus far very imperfectly 

 known, because it was described and figured from a mutilated specimen Ijy Cha- 

 misso, and has not been ol^served since ; Imt the parts preserved agree so fully 

 with Gegenbaur's Eurampha'a, that the close affinity of the two can hardly be 

 doubted. I allude to Chamisso's Callianira heteroptera (Nov. Act. Acad. Nat. 



