202 CTENOPIIOR.E. Part II. 



order of the Ctenoplior* Lobata\ for a small family, of which the genus Calymma 

 Esch. is the type. This family does not correspond to Lesson's tribe Calymmea>, 

 for under that head Lesson unites some Bolinida3 and some true Mnemiidai with 

 the genus Calymma. As limited here, the family of Calymmida? represents a 

 morphological step beyond the Mnemiida?. We have seen that in the family of 

 Bolinid;^ the lobes formed by the actinal prolongation of the anterior and posterior 

 spheromeres are not separated from the spherosome along the lateral spheroineres, 

 but are simply an extension of the actinal portion of their respective spheromeres. 

 Li the Mnemiida}, the separation of the lobes from the spherosome extends in the 

 shape of a furrow along the lateral spheromeres, which the lobes overlap. In the 

 Calymmida% judging from the figures of Mertens, the actinal region and the sides 

 of the spherosome are rendered still more independent by the course of the lateral 

 rows of locomotive flappers and the preponderance of the coeliac diameter. Con- 

 trary to the disposition of the Bolinida-, the anterior and posterior rows of loco- 

 motive flappers are the shorter ones, and the lateral pairs, instead of trending 

 in the direction of the actinal diameter, run Ibrward and Imckward and form 

 arches in an antitropic direction at the point where the auricles arise, thus leaving 

 on each side a broad lateral area luicovered, the centre of which is occupied by 

 the coeliac cavity. Besides Calymma, I think that Lesson's genus Bucejihalon 

 belongs to this family. Owing to the imperfect illustrations of the genus Axiotima, 

 I am unable to decide whether it also belongs here or with the Bolini(U\?. 



The iamily of Ocyroid.e, Lesson's tribe of Ocyroea^, constitutes, morphologically 

 considered, the counterpart of the Calymmid*, as far as I can judge from Bang's 

 illustrations. The actinal region of the spherosome seems entirely free from the 

 anterior and posterior lobes, which, instead of arising from an actinal prolongation 

 of their respective spheromeres, as in the Bolinida^, are formed by an abactinal 

 development of the anterior and of the 2^"^terior spheromeres. MoreoAer, each 

 lobe is bilobed, indicating clearly that it is formed of two spheromeres, corresponding 

 to the lateral spheromeres and their respective auricles. The lateral rows of loco- 

 motive flappers trend in the direction of the cceliac diameter, as in the Calynnnida^, 

 Ijut are very short, in conformity with the actinal jn-ojection of the central part 

 of the spherosome, and give rise to auricles, the base of which is nearer the 

 abactinal poles than in any other lamil}^ Owing to their bilobed form, the anterior 

 and jDOsterior lobes resemble strikingly the auricles. They are, in fiict, the morpho- 

 logical e<|uivalents of the auricles, only much larger, soldered together, and sup- 

 porting long rows of locomotive flappers ; while the auricles of the four lateral 

 spheromeres are free and short. The view which Bang has published of Ocyroe 

 maculata as seen from the abactinal pole is one of the most instructive illustrations 

 extant for the study of the morphology of the Ctenophora\ 



