ON THE NOMENCLATURE AND CHARA(TERISTlCS OF 

 THE LAMPREYS. 



By Theodore Gill, m. d., ph. d. 



In 1870, Dr. Giinther took up the name Pctromyzon hrancMalu for 

 what was before generally called P. plancri. In 188ii, assuming the 

 correctness of that determination and that there were good reasons for 

 the identification, I accepted it and also the \Mime Ammoca'tes, based on 

 the P. hyanchiaJis, for the genus called Lampetra by Gray. It was with 

 much reluctance that I took such a step, and only in deference to the 

 rules of nomenclature regulating such cases, common among the aca- 

 lephs, especially the hydroids, but rare among vertebrates. The reluc- 

 tance to adopt the name Ammoccjetcs with this new range has, I am sure, 

 been shared by many others, and expression has lately been given to 

 it by Prof. Gage in his valuable memoir on "The Lake and Brook 

 Lampreys of New York" (Wilder book,]). 437). Prof. Gage's own 

 researches appear to furnish a perfectly legitimate way out of the 

 dilemma. 



According to Prof. Gage {op. eit., p. 456), "up to the present time 

 there has been no way discovered of distinguishing the larvae of the 

 lake and of the brook lamprey. As the two species occupy the same 

 spawning ground and sometimes spawn in the same nest great care is 

 necessary in order not to confuse the two. After the larvw leave the 

 nest they apparently go to the same sand bed."* 



* The after life of the species is, however, quite different. 



"The brook lamprey does not apparently increase in length after transformation, 

 for many of the transformed ones at the spawning season are of less size than the 

 jnst transformed ones." 



" The lake lamprey npon transforming is only abont one-half to one-fonrtli flie 

 length and probably not one-tenth bulk of the spawning ones." (Gage, op. cit., pp. 

 452,453.) 



A lamprey half the length of another wonld equal an eighth of the bulk, and one 

 a fourth the length would only reach one-sixty-fonrth the bulk, if the proportions 

 corresponded. 



Proceedings National Museum, Vol. XVII— No. 980. 



107 



