108 NOMENCLATURE OF THE LAMPREYS— GILL. vol.xvii. 



As Prof. Gage had uinisual opportunities for investigation, and 

 "since 1875 lost no opportunity of studying the lampreys at all stages 

 of life" {op. cit.y p. 423), his conclusions are especially valuable, and 

 may be safely used in a reconsideration of the question of nomencla- 

 ture. 



Why has Ammocoeies brancMalis, then, been identified specifically 

 with Petrorm/zonplaneri, thus necessitating the restoration of the former 

 name ? 



AMMCECETES COMMON TO ALL AECTOG.EAN LAMPEEYS. 



The memorable researches of Dr. August Miiller, resulting in the 

 discovery that an Ammoccetes was simply a larva of a lamprey, hap- 

 pened to be conducted where the Fetromy.zon planer i was the species at 

 hand, and, inasmuch as the larvte in his possession developed into 

 Petromyzon planeri, the identification was correct. The mistake (if it 

 can be considered as such) was in assuming* that every Ammoccetes vf -as 

 a larval Petromyzon pJaneri, and that the Ammoca'tes or P. hrancliiaUs 

 of Liune was specifically identical with P. planeri and with that alone. 



It now appears that what would be determinable as an Ammoccetes 

 hrancliiaUs may be the larva of any arctognean lamprey, inasmuch as 

 the lake lamprey [Petromyzon marinus var.) and brook lamprey [Lam- 

 petra sp.*) are most distinct from each other. Inasmuch also as the sea 

 lamprey {Petromyzon marinus) ascends fresh-water streams to breed, 

 there was no reason for identifying P. hranchialis with one rather than 

 another species, the definition applying to one as well as to another, and 

 doubtless the larvfe of the three Euroi)ean species (P. marinus, P. fluvia- 

 tilis^ and P. planeri.) have been frequently, if not habitually, confused. 

 It follows, therefore, that P. hranchialis (Linne) and Ammoccetes are 

 generic rather than specific synonyms and should be so treated. The 

 name Lampetra may be, consequently, revived for the fresh-water 

 lampreys of Europe and eastern America and the synonymy digested 

 as follows. 



SYNONYMY. 



Genus PETROMYZON. 



< retromyzon, LiNNiEUS, Syst. Nat., ed. 10., v. 1, p. 230, 17.58. 



<^ Petromyzon, (Dumeril) Cuvieh, Regne Auimal, t. 2, p. 118, 1817. 



< Avivwcoctes, (Dumkril) Cuvier, Regne Auimal [1« ed.], t. 2, p. 119, 1817 (based 



on larval form). 

 = Pefromyzou, Gray, Proc. Zool. Soc. Loudon, pt. 19, pp. 235, 236; List Specimens 



Fish Brit. Mus., pt. 1, p. 137, pi. 1, f. 1 (mouth), 1851. 

 = Lampetra, Malm, Forhandl. Skand. Naturf., 8. niilde, p. 580, 1860. 

 <^ Petromyzon, Gunther, Cat. Fishes Brit. Mus., v. 8, p. 500, 1870. 



* The specific identity of either the European Lampetra planeri "or L. jturxatiUs with 

 an American species is very doubtful and at least requires verification. 



