522 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



PETROMYZONTIN^. 



Synonymy. 



<[ Lanipredia, Eafinesque, Analyse de la Nature, p. 94, 1815. 



< Petromyzoniiii, Bonaparte, Giorn. Accad. di Scienze, v. 52 (Saggio Distrib. Metod. 



Auimali Vertebr. a Saugue Freddo, p. 41), 1832. 

 <] PetrouiyzoDini, Bonaparte, Nuovi Anuali delle Sci. Nat., p. 133. 1838; t. 4, p. 277, 



1840. 

 <^ Petroniyzontiformes, Bleeker, Enum. Sp. Piscium Archipel. Indico, p. xxxiii, 1859. 



Young. 



> Ammocoetiua, Gray, Proc. Zool. Soc. Loudon, 1851, p. 235, 240; List Fisli. B. M., 



pp. 137, 145, 1851. 



> Aramocoetini, Bonaparte, Cat. Metod. del Pesci. Europei, p. 92,* 1846. 



^ Ammocoetiformes, Bleelcer, Euum. Sp. Piscium Arcbipel. Indico, p. xxxiii, 1859. 



Petromyzoutids with the suproral lamina median and undivided. 



Analysis. 



I. Lingual teeth of anterior row coalesced into one; suproral lamina bicuspid or 

 tricuspid. 



1. Discal and peripheral teeth in obliquely decurved continuous rows; suproral 



lamina contracted. 

 la. Suproral lamina bicuspid; anterior lingual tooth with a deep re-entering 



median groove terminating in a point retromyzon. 



16. Suproral lamina tricuspid ; anterior lingual tooth with a slight median 



groove Ichtliyomyzon. 



2. Discal and peripheral teeth differentiated; former vertically uniserial and bi- or 



tri- cuspid ; latter uniserial and minute ; suproral lamina extended laterally. 

 2a. Suproral lamina bicuspid ; anterior lingual tooth with a crescentiform dentated 



edge and the median denticle enlarged Ammocates. 



26. Suproral lamina tricusjjid ; anterior lingual tooth wedge-shaped, and with an 



almost straight, finely serrate edge Entosplienns. 



II. Lingual teeth of anterior row two, distinct and conic ; suproral lamina quadri- 



cuspid Geotria. 



III. Lingual teeth three, standing on the same base, pointed and curved ; the median 

 smallest Exomegaa. 



PETROMYZOK 



Synonymy. 



— Petromyzon, Linuwus, Syst. Nat., ed. 10. 



< Petromyzon (Dumeril), Cuvier, Regne Animal, t. 2, p. 404, 1817. 



< Petromyzon, Gray, Proc. Zool. Soc. London, pt. 19, p. 235, 236; List Specimens Fish 



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

 = Lampetra, Malm, Forhandl. Skaud. Naturf. 8 mode, p. 580, 1860. 



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



Petromyzon tiuse with the suproral lamina contracted and with two 

 converging teeth; introral lamina multicuspid; disco-peripheral teeth 

 numerous, and in arched series (of 4 to 6 each) declining downwards; 



