No. 2194. XORTII AMERICAN PARASITIC COPEPODS— WILSON. 89 



Remarks. — The present is one of the longest known and most fre- 

 quently mentioned species amongst the parasitic copepods. Every 

 zoologist has become familiar at least with its name and some of its 

 reputed characteristics. It has long served as one of the stock ex- 

 amples used to illustrate degeneration and retrogression, and the aver- 

 age opinion with reference to it has been well expressed by Dr. 

 Andrew AVilson in an article on Degeneration in the Popular Science 

 Monthly for June, 1881, in which he said "Beginning life as a three- 

 legged 'nauplius,' the lernean retrogresses and degenerates to be- 

 come a mere elongated worm, devoted to the production of eggs, f<nd 

 exhibiting but little advance on the sacculina" (p. 227). 



The appendages have been variously reported as rudimentary or 

 entirely obsolete, even up to the very latest publications with refer- 

 ence to them. At the time of the first discovery of the male by 

 Metzger and Claus (18G8), the latter called particular attention to 

 the presence of a compound eye, of anal laminae, and of the various 

 appendages in the adult female, but the significance of his discov- 

 eries were overlooked and soon forgotten. As far as the appendages 

 are concerned, the present species shows neither retrogression nor 

 degeneration. The adult female retains all the appendages that she 

 ever possessed, and they are as fully developed in the adult as they 

 were in the copepodid stage. The only change that has been made is 

 that the parasite has ceased to use some of them, and they have con- 

 sequently become brittle and are easily broken oif. And even if we 

 apply to them the term rudimentary, we must remember that they 

 are no more imperfectly developed in the adult than they were in 

 the larva. In the body form there is an elimination of joints, more 

 or less fusion of various body regions, and considerable distortion, 

 so that here w-e do find retrogression. In the future, therefore, in 

 dealing with this species we should remember that the appendages 

 can not be classed with the body form, but that the two are dis- 

 tinctly separate. 



Genus LERNAEOLOPHUS Heller. 



PcnncUa (part) Nordmann, Galerie du Museum d'Hlst. Nat. de Paris, 1839; 



P. sultana, afterward made the t.vpe of Heller's genus; Bull, de la Soc. 



Imp. des Nat. Moscou, 1SG4, vol. 37, p. 485, P. sultana, var. sifpnolda. 

 Pcncllus (part) Milne Edwards, Histolre Naturelle des Ciustiices, vol. 3, 



1840, P. snltaiia, p. 523. 

 Lcmaca (part) KR0YFn?, Naturhistorisk Tidsskrift, 3 Raekke, 2 Bind, 18G3, 



L. hcmiraiiiphi, p. ,S1S, afterwards transferred to Heller's irenus. 

 Lernaeolophns Hkllkk, Reise dor Novara, 186.1, p. 251, L. sultdnioi. mono- 



typic. 

 Lernaeolophns AVu.son, Proc. U. S. Nat. Mus., vol. 44, 1913, L. rccnrvus, 



p. 252, pi. 4G; L. striatns, p. 2.54, pi. 47, figs. 2G0, 201. 



External generic characters of female. — Cephalothorax inclined 

 ventrally to the neck axis; a pair of lateral and an unpaired dorsal 



