438 ME. p. W. BASSETT-SMITH ON [Apr. 18, 



The following papers were also read : — 



1. A Systematic Description of Parasitic Oopepoda found 

 on Fishes, with an Enumeration of the known Species. 

 By P. W. Bassett-Smith, StafP-Surgeon R.N., F.Z.S., 



F.R.M.S. 



[Eeceived March 1, 1899.] 



(Plate XXVI.) 



The number of known Copepoda parasitic upon fishes has been 

 gradually increasing of late years : and their peculiar modes of life, 

 exti-aordinary forms, and the remarkable positions in which they 

 are found have caused them to be an interesting study to those 

 naturalists who are working in marine zoology, especially if they 

 have been in the habit of handling fishes when recently caught. 



Prom a morphological point of view the lower types are the 

 more interesting, as exemplifying the effect of parasitism on the 

 females, which lose more and more their ordinary appendages, 

 becoming nothing better than fixed saccular animals, capable of 

 imbibing nourishment and producing progeny ; while the male, 

 though often of very minute size, retains its general crustacean 

 appearance. These points have repeatedly been investigated by 

 Carl Vogt, Kurz, Glaus, and others. 



The literature on the subject is widely scattered, and many of 

 the animals have exceedingly long lists of synonyms. Ifc has been 

 my object in this paper, which I trust will be of use to future 

 workers, to gather together this material, and to put it into a 

 workable form, as a basis for further investigation. 



The latest attempt to systematize this group was made by 

 A. Gerstacker in Bronn's ' Class, und Ordn. des Thier-reichs,' 

 1866-1879, Crustacea, vol. v., Copepoda, which admirable work I 

 have followed very closely, excepting in some groups which are 

 mentioned later on. He has very largely based his classification on 

 the structure of the articulate organs, which appears to be the most 

 certain and scientific method. As the more lowly organized groups 

 are reached, viz., those in which the female has lost almost all its 

 articulate appendages, the characters and conformation of the 

 males become most valuable guides : these being often very minute 

 or pigmy-like. In many cases they are quite unknown, and are 

 therefore a good field for further work, the discovery of new forms 

 being very pleasing. There is no doubt that continued research, 

 especially on the non-edible fish, in different parts of the world, 

 would be rewarded by the discovery of a great number of new 

 forms, and, what is badly wanted, further specimens to establish 

 genera, many of which have been recorded by a single observer 

 onlv, and not infrequently from one specimen only. 



In a large number of cases the descriptions and plates found in 

 the older works are most indefinite, making the diagnosis of the 



