4 PROCEEDINGIS OF THE NATIONAL MUSEUM. vol.53. 



had been described by Gissler under the name Pediculus salvionis.,^ 

 arranging the three species in the order named. 



Accordingly the species cypinacea^ upon which the genus was 

 originally founded, and which stands first in this tenth edition, be- 

 comes the oldest species in the family. It was the ostensible genus 

 type for nearly a century, and it may well be restored to that posi- 

 tion. 



The second species, asellina.^ is a typical Chondracanthid, while the 

 third, salmonea, is as tj'pical a Lernaeopod, so that neither of them 

 can be even retained in the family. 



In the twelfth edition another new species, hranchialls, was added 

 to the genus and was placed first, but the genus diagnosis remained 

 unchanged. 



For many years every newly discovered parasite, whatever its 

 structure might be, was referred to the genus Lernaca, which thus 

 came to include a large number of heterogeneous species. jMany of 

 these have since been established as distinct genera. The first to be 

 thus established was the species hranchiah's, which was made the type 

 of a genus called " Leryieoccra'''' by Blainville in 1822 (p. 370). 

 Blainville included in his genus, besides the species hroncIiiaUs, 

 Miiller's Lernaca cycloptcrina^ a new species which he named sur- 

 rj.j'a.iis, and unfortunately Linnaeus's Lernaca cyprlnacca. If he had 

 only omitted this last species, which of course he had not the 

 slightest excuse for including, since it was Linnaeus's type species, 

 the two genera would never have been exchanged, but, as it was, his 

 mistake was copied by Desmarest (182.')), Nordmann (1832), Bur- 

 meister (1833), Kr0yer (1837), and Milne Edwards (1840). The 

 latter explained that Nordmann, Burmeister, and Kr0yer had re- 

 stricted Blainville's generic name to such species as had soft sym- 

 metric horns on the head and straight multiseriate Q^g strings, and 

 he adopted their restriction. Blainville, however, distinctly stated 

 in his genus diagnosis that Lernaeoccra had three immovable and 

 branched chitin horns, two lateral and one dorsal (p. 375). And 

 under the type species he said, " The egg sacks arise from just in 

 front of the posterior extremity of the body and are much twisted 

 or coiled" (p. 370). Furthermore, he stated plainly that he had 

 never seen the species cyprinacea., but only the figure published by 

 Linnaeus, which did not shoAv the Qgg sacks. 



In other words, the authors above quoted deliberately exchanged 

 the two genus names to suit their own fancy, took away from Lin- 

 naeus's genus Lernaca the species which had served as its type for 90 

 years, and substituted for it the species which Blainville had made 

 the type of his genus Lernaeoccra., and forced upon Blainville, as a 



« Kongl. Svensk. Vetensk. Acad, llandlingar, 1751, vol. 12, p. 185, pi. C, figs. 1 to 5. 



