ECHINODERMATA OF NEW ENGLAND. 49 



cavity. Chymiferous tubes anastomosing, with many lat- 

 eral branches. 



B. roseola. 



B. II. 



Pleurobracliia . Body spherical, transparent, colorless, 

 of relative hard consistency. Meridional rows of flappers 

 of equal length extending direct from the sense to the oral 

 pole. Tentacles very long with lateral branches of crim- 

 son color, capable of being retracted into ;i chamber on 

 each side of body. 



P. rJiododactyla. 



Mnemiqpsis. 1 Body transparent, compressed laterally 

 and with two prominent lobes. Body colorless, with 

 walls flexible. Tentacles short. Rows of locomotor flap- 

 pers of unequal length. Four ear-like, ciliate ( ?) ap- 

 pendages ("auricles") near the mouth. 



M. Leidyi. 



Free-swimming larvae. 



The larva? of the Ctenophora are among the most com- 

 mon of all the medusa' found in surface- fishing. The eggs 

 sometimes occur in great numbers in the collecting jars 

 where any of the different genera have been allowed to 

 remain fora short time. They are sometimes found single, 

 sometimes in strings. Ova are small when single as in 

 Mnemiopsis and others, but can be observed with the 

 unaided eye. These little transparent globes enclose an 

 egg, the growth of which can easily be followed through 

 early stages of segmentation. The larva? of the Cteno- 

 phora, after leaving the egg sac, are difficult to refer to 



1 Bolina alata is closely allied to this genus. 

 ESSKX INST. BULLETIN, VOL. XXIII. 4 



