304 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.39. 



this family only one or two could be found with spermatophores. 

 We thus haA'^e another link in the chain of evidence which goes to 

 prove that the union of the sexes takes place while they are still 

 swimming freely at the surface and before they have sought out a host. 

 Or rather before the female has sought one out, for the male remains a 

 free swimmer throughout life. 



It also furnishes strong proof that a single union supplies the 

 female with enough spermatozoa to fertilize many broods of eggs, if 

 indeed it is not enough for all she will ever lay. 



Furthermore, it explains incidentally the fact that no males are 

 found with the females at an^^ season of the year, upon the host which 

 the female may have selected. 



Family ERGASILID^. 



Historical. — In spite of the fact that the present family of copepods 

 stand as a connecting link between the two great groups of free- 

 swimming and parasitic forms, they have not received as much atten- 

 tion as would be expected from authors who have dealt with either 

 of these groups. Perhaps the fact that they do thus occupy a middle 

 ground has had some influence in causing the neglect. Authors who 

 were dealing with the free-swimming forms would not naturally include 

 this family of parasites. And on the other hand, those who have 

 described the true parasitic forms, degenerate or with modified mouth 

 parts, have been satisfied with merely mentioning these tiny creatures, 

 in which parasitism has as yet produced but little change. And 

 even the few investigators who have taken up especially the interme- 

 diate semiparasitic families have almost without exception neglected 

 the Ergasilidfe. Possibly this is due to the fact that they are fish 

 parasites, while all the others live on invertebrate hosts. 



The family was founded in 1832 by Nordmann, who established 

 the two type genera, Ergasilus and Bomoloclms , the former with three 

 species and the latter with one. Nordmann gave an excellent digest 

 of the genus Ergasilus after a comparison of his three species, and 

 included even some of the development stages. For the genus 

 Bomolochus he had but a single species and contented himself with a 

 description of that, making no attempt at a genus diagnosis. But he 

 found no males of either genus, and while he inferred that there would 

 be a difference between the sexes similar to that in Cyclops, there was 

 no direct proof. He recognized the close relationship of the two 

 genera, but left them without creating any new family for their recep- 

 . tion. This was done in the following year by Burmeister in his work 

 on the parasitic copepods (1833), who placed the new family, Ergasi- 

 lina, between the Caligina and the Lernseoda. He included in the 

 family not only Nordmann's genera Ergasilus and BomolocJius, but 

 also the Lamproglena of the same author, Audouin's Nicothoe, 



