524 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 

 A partial synonymy of the type is as follows : 



ENTOSPHENUS TKIDENTATUS. 



Synonymy, 



1836 — Petromyzon triclentatus, Gairdner, MSS. 



1836 — Pttrom yzon trideutatus, Richardson, Fauna Boreali-Americana, v. 3, p. 293, 1836. 



1842 — Petromyzon tridentatus, DeKay, Nat. Hist. New York, v. 5, p. 381. (Extra- 



limital.) 

 1846 — Petromyzon tridentatus, Storer, Synojisis of the Fishes of North America (p. 266) 



in Mem. Am. Acad., v. 2, p. 518. 

 1851 — Petromyzon tridentatus, G7-ay,FToc. Zool. Soc. London, pt. 19, p. 240; List 



Specimens Fish in Brit. Mus., p. 144. 

 1858 — Petromyzon lividus, Girard, Expl. and Surv. for E. R. Route to Pacific Oc, v. 



10, Fishes, p. 379.' 

 1862— Entosphenus tridentatus, Gill, Proc. Acad. Nat. Sci. Phila., [v. 14,] p. 331. 

 1870 — Ichthyomyzou tridentatus, GUnther, Cat. Fishes Brit. Mus., v. 8, j>. 506. 



Habitat. — California. 



•GEOTRIA. 



Synonymy. 



> Geotria, Gray, Proc. Zool. Soc. London, pt. 19, p. 239, pi. 4, f. 3, (mouth,) pi. 5, 

 (tish,) 1851; List Specimens Fish in Brit. Mus., pt. 1, p. 142, pi. 1, f. 3 (mouth), 

 pi. 2 (fish), 1831. 



^ Velasia, Gray, Proc. Zool. Soc. London, pt. 19, p. 239, pi. 4, f. 4 ; List Specimens 

 Fish in Brit. Mus , pt. 1, p. 143, pi. 1, f. 4 (mouth), 1851. 



= Velasia, Giinthrr, Cat. Fishes Brit. Mus., v. 8, p. 508, 1870. 



PetromyzoutinaB with the sni)roral lamina transversely extended and 

 arched, armed witli " four sharp flat lobes," the outer of which are en- 

 larged ; the infroral lamina crescent-like, sinuous, or denticulated on the 

 edge ; tlie discal teeth numerous and in diverging series, and the lingual 

 teeth elongated, conic, and two in number (Gray and GUnther). 



EXOMEGAS. 



Synonymy. 

 — Exodomegas, Gill MSS. 

 Petromyzon sp. Biirmeister. 



Petromjzontidse with the discal teeth in concentric series, the outer 

 containing the largest teeth (about 24 on each side), lingual teeth three, 

 large pointed and curved, the median smallest, all standing on the same 

 base. 



Type JExomegns macrosfomus = Petromyzon macrostomus Biirmeister^ 

 Anal. Mus. Buenos Aires, pt. 5, 18G8, Acta Soc Palaeont., p. xxxvi. 



CAEAGOLIN^. 



Synonymy. 

 Caragoliuaj, Gill, MSS. 



Petromyzontids with two lateral suproral laminae. 



