1. I'lMROiMVZMX. OOl 



I\;lr()niy/.i)ii vt Lainpctra, (irai/, Cliondropt. p. \A'-\. 



Larvd: Ainmoccutos, (Dunicril) Cuv. Reyne An. 



Larva : ScolecoaoiUca, (/hard, U. S. Pac. R. R. Expcd. Fish. p. .'{84. 



Dorsal tins two, the posterior continuous with the caudal. The 

 maxillaiy (k'lititiou consists of two cceth placed close together, or 

 of a transverse bicuspid ridge ; lingual teeth serrated. 



Coasts and fresh waters of the northern hemisphere. 



]*rof. Aug. ^liillcr (Miiller's Archiv, ]8d(!, p. 325) has shown 

 that the tishes of this genus arc subject to a metamorphosis, the 

 larval form having been hitherto known as Ammocoetes. He has 

 proved the truth of his discovery by tracing the development of 

 Ammocoetes branchialis into Petromyzon pluneri. It may be assumed 

 that not only the Petromyzons proper, but also the fishes of the 

 allied genera undergo a similar metamorphosis. 



Ammocoetes branchialis retpiires three or four years for its com- 

 plete development. In the larval state the head is ver}'' small, and 

 the buccal cavity is surrou7ided by a semicircular upper lip, the 

 isoparate low^er lip being very small. There are no teeth, but several 

 fringed barbels surround the mouth. The eyes are extremely small, 

 hidden in a shallow groove. A median single nasal opening and 

 seven gill-openings, as in the adult. The vertical fins form a con- 

 tinuous fringe, in which the later divisions are more or less dis- 

 tinctly indicated. Species described as Ammocoetes and distinguished 

 by their authors on account of modifications of the organs subject to 

 metamorphosis, are, of course, quite inadmissible. 



On the numerous publications on the anatomy of the Lampreys, 

 consult Engelmann & Cams, liiblioth. Zoolog. pp. 1030-1031. 



1. Petromyzon inarinus. 



The Sea-Lamprey. See-Neunauge. Lamproie. Nejonogon (Swcd.). 



Lampetra s. Mustela, Rcllo/i. l)e Aqiiat. p. 70 ; Rondel, p. 398 , 

 Wilkujhhy, p. lOo, tab. 2. fig. 2. 



Lampetra maculosa, Salvian. f. ('>3 a. 



major, Salvian. f. Go b ; Aldrov. p. 539 ; Jo?>sfon. Dc Pise. tab. 



24. f. r,. 



Petromyzon, sp. no. 2, Artcdi, Si/nnn. p. 90 ; Gen. p. 04. 



Petromyzon marinus, L. Sj/st. Kat. i. p. 394 ; Kau, Srhrift. Ges. 

 ntrf. Frvund. Bcrl. vii. p. 460 ; Schnpff, Schrift. Ges. ntrf. Fnund. 

 Berl. viii. p. 184 ; Bl. Fisrh. Dcut^rhl. iii. p. 38, taf. 77 ; 7>V. Si-hn. 

 J). o30; Lacon. i. p. 3, pi. 1 ; Mitch. Lit. is- Phil. TranJi. New York, 

 1. p. 401: Thu'ir. lirit. Fi.sh. pi. 81; Flem. Brit. An. p. J(i3; 

 Midler, Abhandl. Ah. Wiss. Berl. l.S.]4, p. 78 ; Parnell, i'V.sA. Firth 

 of Forth p. 282 ; Yarrrll, Brit. Fi.sh. 2nd ediU ii. p. r)^)H, or, 3id 

 edit. i. p. 32; Grai/, Chondropt. p. 13S, or Pruc. /.ool. S'oc. 1851, 

 p. 235, pi. 4. fig. 1 ; A7/.S-.. Shand. Faun. Fid: p. 743 ; Seli/.s-Lonf/ch. 

 Faun. Jielf/e, \>. '2'2C) ; Kriiifcr, Danm. Fiak. iii. p. 1025; Giinth. 

 Juxch. Xrckar's, p. 131 ; IL'ikel Si' Kner, Siissicas^crf. p. .374, figs.* 

 200 .<c 201 ; Siebold, Siisxwa<serf.-p. 308 ; Bert, Ann. Se. Xat. 18(l7, 

 Aii. p. 371 ; Blanrhurd, 7'o/s.v. France, p. 512; Canc.strini, Arch. p. 

 I" Z'lol. iv. p. 1)^1. 



