126 



THE OCEANIC HYDROZOA. 



diflScult to come to any clear conclusion on this head. Apparently from the discoloration of 

 the specimens, there is no distinguishable white renal organ, but I have met with many 

 minute crystals and granules similar to those considered to be Guanin by Professor Kolliker. 

 Not having had any opportunity of examining Forjjita tiiediterranea, I will not enter upon the 

 consideration of the apparent differences in structure between that species and the one which 

 I have studied. 



It would be very interesting to trace out the development of Porpifa, but, from the 

 observations I have detailed respecting Felella, I have little doubt that the early state of the 

 two forms is very similar ; and that, in Porpita as in Veldla, the sinuses must be regarded as 

 the somatic cavity cut up and subdivided by the union of the opposed layers of the 

 endoderra. 



The most remarkable feature in the organization of both genera, however, is the 

 penetration of the hydrosoma by the pneumatic and other tubercles on the proximal, and bv 

 the pneumatic filaments on the distal side. 



/' i' r 



Desceiption op TiiE WooDCUTs. — A. Diagram of a radial section of the large Po;'/)j7a. o. The distal oi 

 inferior layer of the hydrosoma. V. The gonoblastidial polypites with their gonophoric buds, among which the 

 pneumatic filaments, f^, are seen twining, c. The tentacles, d. The limb. e. The proximal or superior layer of 

 the hydrosoma. f*. The pneumatic apertures. _/''. The tubercles of the proximal layer of the pneumatocyst. 

 /'". The air-chambers, f^^. Their prolongations into the lamella. B. One of the urn-shaped pneumatic apertures. 

 C. Diagram of a transverse, or tangential, vertical section of Porpita, 



