530 ON NEW SPECIES ETC. OP MEDUSiE. 



or adjacent ovaries, and occasionally to three. More rare is the 

 case of total suppression of one ovary. Only on about a dozen 

 occasions have I seen total suppression of two ovaries ; and in 

 these it was sometimes the adjacent, but more frequently the op- 

 posite, organs that were missing. Lastly, on one occasion I ob- 

 served, in an otherwise well-grown specimen, a total absence of 

 three out of the four ovigerous pouches. In no case, it may be 

 added, did I observe that a deficiency or absence of ovigerous 

 pouches entailed any corresponding deficiency or absence of any 

 other organs. 



I have said that, so far as my experience extends, neither re- 

 duction nor complete suppression of parts appears to occur in 

 any organs of A. aurita other than the ovaries. It therefore be- 

 comes necessary to add that one or more of the lithocysts, together 

 with their hoods, are frequently to be seen of smaller size than the 

 others. As tliese variations, however, are usually attended with 

 a deficiency of the general tissue of the umbrella in the neigh- 

 bourhood of the affected lithocyst, I am inclined to believe that in 

 these cases the small lithocyst is one that has been reproduced 

 to repair the loss of the original organ, which I suppose to have 

 been removed by mechanical violence of some kind — a mutilation 

 which seems well indicated both by the deficiency just alluded to 

 of umbrella- tissue in the parts concerned, and also by the cicatrix- 

 like appearance which is presented at the confines of these parts 

 by such tissues as remain. 



In conclusion, I may state that towards the end of August all 

 the individuals of this species began to undergo a marked 

 diminution in size. Concurrently with this diminution in size, 

 the intensity of the pink colour (which in this species is charac- 

 teristic of the ovaries, nutritive system, and tentacles) underwent 

 a marked decrease ; so that at last I was only able to obtain 

 specimens one half or one quarter the ordinary size ot Aurelia 

 aurita, and having nearly all their natural rose-pink colour dis- 

 charged. I believe that these two phenomena — the loss of colour 

 and the diminution in size — are related to one another in a very 

 intimate manner. Just at the time of year when these two pheno- 

 mena began to manifest themselves, I observed that all the speci- 

 mens oiAurelia I met with were infested by a species of crustacean 

 {Hyperia galhd), which lodged chiefly in the ovaries and nutritive 

 canals. These crustaceans appeared to devour with avidity all 

 the coloured parts of their hosts ^ and I think it was probably due 



