12 Bulletin 47, United States National Museum. 



lamprey, foniul in the North Pacific, similar inhabittoPe<ro)()i/-o» marinxis 

 of the Nortli Atlantic, (^vrof, within ; o'i^'nv, wedge; the lingual tooth 

 being wedge-shaped.) 



11. ENTOSPHENUS TRIDENT ATUS, (Gaiidrui). 



Lips thick, fringed with numerous p.apill*, within which are small 

 teeth. Infraoral lamina with 5 or 6"cusps; buccal teeth before mouth 

 nnicuspid, those on sides larger, the first and last bicuspid, the middle 

 ones tricuspid; median supraoral cusp little more than i the length of 

 the other 2 ; first dorsal fin distant about g of its own length from the 

 second. Head 8 to 10 in length ; 73 muscular impressions between gill 

 openings and vent. Color, plain dark brown, rarely mottled. Pacific 

 coast of America, Unalaska to Southern California; ascending streams to 

 spawn, going as far as Walla Walla, in the Colum])ia, its range southward 

 extends to Santa Ana River at Riverside, California. L. 18 inches or 

 more, {tridentahis, three-toothed.) 



Petromy::nn Iridentatm, (Gairpner MS.), Richardson, Fauna T?or. Am., 29P., 1836, Falls of the 



Walamet, now Willamette. 

 Pelrmmjzon cilialus, Ayres, Proc. Cal. Ac. Sci., 185">, 44, San Francisco. 

 Pelromyzon lividm, Girard, Pac. R. R. Surv., 379, 1858, Wahlahmath River, Oregon ( Vv^illa- 



mette River.) (Type, No. 97G.) 

 Petromyzou astori, GiRARP, I. c, 380, 18.58, Astoria, Oregon. (Typo, No. 978.) 

 Ichlhijomyzon IruloUatiis and (istori, GU.vther, Cat., vni, 50G, 1870. 

 Enlosphenns epihexodon, Gill, Proc. Ac. Nat. Sci. Phila., 18rj2, 331, Fort Reading, California 



after Girard. 

 Lampelm Iridentata, astori, and epihexodon, Jordan & Gilbert, Synopsis, 7, 8, 1S83. 

 Ammocoeles (ridentatus, .lORDAN & Fordice, I. c, 291, 1886. 



9. LAMPETRA,- Gray. 

 (Brook Lampreys.) 



Kampelrn, Gray, Proc. Zoiil. Soc. London, 18.51, 235, {ihn'i(du's). 



Lampreys of small size, with the dorsal fin eraarginate or divided into 

 two parts, the posterior portion continuous with the low anal fin around 

 the tail ; supraoral lamina broad, forming a crescentic plate, with a large 

 bluntish cusp at each end, and rarely a very small median cusp; lingual 

 teeth small, with a crescent-shaped dentate edge, the median denticle 

 enlarged; buccal disk small, its teeth few imd never tricuspid. Small 

 lampreys, inhabiting the brooks of Europe and North America. Five or 6 

 species known, bearing much the same relation to Entosiilienns that Ichthy- 

 omyzon bears to Petromyzou. {lambere, to suck; j)etra, stone.) 



a. Dorsal fln divided into 2 parts which are separate, or joined at base only. 



* The name Ammococtes was originally applied to the larval forms of Pelromyzotiids wliirh are 

 in that stage specitically indistinguishable and which were supposed by Dumeril and Cuvicr to 

 be geuerically distinct from the adult forms. After the identity of the two was discovered, the 

 name ylmmoca?(e« was used by many writers, following a suggestion of Milne-Edwards, as a gen- 

 eral term to bo applied to the blind or larval stage of all lampreys. Lampelra of Gray should 

 therefore be used for this genus, for which it was originally proposed. Inasmuch as no Euro- 

 pean Ammocales can bo referred to any determinate species of Pctromyzonid, the nominal genua 

 corresponds with Petromyzonaa a whole and not to any subdivision, 



