Jordan and Evcrmann. — Fishes of Nort/i America. 



(Ill Anterior lingual tooth divided liy a mciliaii groove; dorsal tin continuous, 

 with a broad notch. Small lampreys; fluviatile. Iciithyomyzon, 7. 



rr. Siipraoral lamina very large, expanded laterally, forming a crescent-shaped plate 

 with a cusp at either end and sometimes a median cusp ; anterior lingual teeth 

 more or less serrate. 

 e. Supraoral lamina with a well-developed median cusp ; anterior lingual tooth 

 wedge-shaped, its edge finely serrate and nearly straight ; dorsal fin divid- 

 ed ; buccal disk moderate, some of its teeth bicuspid. Large lampreys; 

 anadromous. Ento-^phents, 8. 



ee. Supraoral lamina with a very small median cusp or none; anterior lingual 

 tooth little developed, its edge crescent-shaped and dentate; the middle 

 denticle enlarged; buccal disk small, the teeth small and never tricuspid; 

 dorsal fins separate or deeply divided; small lampreys; fluviatile. 



Lampetra, 9. 



5. BATHYMYZON, Gill. 



Balliymipmi, Gii.i,, Proc. U.S. Xat. Mus., 1883, 2.54, ((joi/Y/iV)- 



Supraoral lamina coutracted,its two converging teeth almost completely 

 fused, and only evident at the summit of the combined mass; infraoral 

 lamina crescentiform and spout-like at the middle and with the den- 

 ticles obsolete: discopeiipheral teeth numerous and in obliquely arched 

 series of 4 to 7, declining downward ; innermost lateral teeth of the 4 rows 

 diverging from mouth, in each side bicuspid, with the cusps approx- 

 imated and diminishing downward rapidly ; lingual teeth 3, pectinate, 

 the anterior deeply impressed and sulcate backward at the middle, and 

 the posterior correspondingly curved backward at their inner lateral 

 angles; the anterior dorsal tin distinct from posterior. (,3aSi%, deep; 



/liCu, to suck.) 



7. B.VTHT.tlTZOX BAIRDII, (Gill). 



Head from snout to first branchial aperture about 7 times in total 

 length ; eye midway between snout and fifth branchial aperture ; diame- 

 ter of l)uccal disk equal to interval between eye and fifth branchial aper- 

 ture, the margin regularly fringed ; indications of 8 teeth on the infraoral 

 lamina; tips of the two supraoral ones barely perceptible ; pectinations 

 of lingual teeth well marked. Chest about as long as snout. Fins mod- 

 erate ; anterior dorsal somewhat higher in front of middle than diameter 

 of orbit, second dorsal about twice as high, or equal to the distance be- 

 tween eye and first branchial aperture. Color dark, belly grayish ; second 

 dorsal darker across middle in front and toward margin behind ; candal 

 blackish throughout. (Gill.) Gulf stream, ouce taken. (Named for 

 Spencer Fullerton Baird.) 



Pelrnmyzon {Balhymijznn) hairdii, GiLL, /. c, 254, 1883; lat. 49'^ N., 547 fathoms; GoODE & 

 Bean, Oceanic Ichthyology, 4, 1894. (Type, No. 33311.) 



6. PETROMYZON, (Artedi\ Linnteus. 

 (Lampreys.) 



Pelromyzon, (Artedi), LiNN.T;r.s, Systema Xatura>, Ed. x, 1758, 230 {marinux). 



AmmoccetKt), (Dumeril), Ouvier, Ri-gne Animal, Ed. I, 119, 1817, {branchialis, larval fonn of any 



or all Eui-opean species.) 

 Ammoaieliii!, Bi.ainville, Faune Franyaiso, liv. xxiv, 3, 1828, {bra)ickialis). 



Lampreys with the supraoral lamina armed with 2 or 3 separate teeth, 

 pointed, and close together, not forming a crescent-shaped plate ; anterior 



