of the, Bay of Naples. 87 



To my astonishment I found upon the Nebalice of the Bay 

 of Naples, with which I was most abundantly provided, not 

 the same genus wliich Claus met witli on the Phyllopods of 

 Trieste, but another one, differing from it in many respects ; 

 but as it agrees in most of its cliaracters of organization with 

 Seison annulatus and Grubii, it may in future bear the name 

 of Paraseison. Its description forms the subject of the fol- 

 lowing pages. 



In all I have seen four species of Paraseison, of whicli, 

 however, only one was to be met with in comparative abun- 

 dance on Nehalice from the middle of March to the middle of 

 April ; the other three, on the contrary, were so rare that, 

 with all my efforts, I was only able to study one or two living 

 females of any of them. I will commence with the common 

 species : — 



1. Paraseison asplanchnuSy sp. n. 



Even this species was not particularly plentiful during my 

 residence in Naples ; on the average only each fourth or fifth 

 Nebah'a was infested by parasites, and it was seldom that 

 more than two or three adult individuals occurred together on 

 the same host. I have no doubt, however, that at a more 

 advanced season of the year these Rotatoria become more 

 numerous, as their abundance was slowly increasing during 

 the time that I was able to observe them. Reproduction 

 seems to be reduced to a very small amount during the winter 

 months, for at the commencement I found only old adult indi- 

 viduals, while later on ova and newly hatched examples were 

 frequently observed. Female animals were always present in 

 greater number than males, but the proportional abundance 

 of the two sexes was by no means so extreme as in the fresh- 

 water Rotatoria ; generally there was one male to six females. 

 The animalcules attach themselves, like the true Seisonidie, 

 by preference to tlie branchial laminte ; but they also creep 

 about upon all the other regions of the body. They attach 

 themselves by means of an adhesive mucus, which is secreted 

 from a number of pedal glands, by the posterior pole of the 

 body to their point of support ; and as we not unfrequently 

 see, near the point of attachment of a female, several ova 

 lying together in different stages of development (in one case 

 1 observed eleven in one mass), it seems to me probable that 



