ACALEPHJ;. 243 



and a terminal aerial vesicle. It is much the same in the Prayse 

 or Diphydse. In this family a great numher of natatory vesicles are 

 connected with the terminal aerial vesicle, as in Fig. 101, Pray a diphys. 

 This species is -widely diffused in the sea which bathes the Nicean 

 coast, but it is very difficult to procure perfect specimens. M. Yogt 



Fig. 101. Praya diphys (Blainville). 



found fragments more than three feet long which swam on the 

 surface, and was in its state of contraction not more than a finger's 

 length. This species has been met with at Porta della Praya and at 

 San Yago, one of the Cape de Yerde islands. 



The colony of the Praya presents two great locomotive bell shaped 

 masses, between which the common trunk is suspended, and to which 

 it can retire. This cylindrical trunk, which is thin and transparent, 



B 2 



