8 CONTRIBUTIONS TO NORTH AMERICAN ICHTHIOLOGY IV. 



sides of the maxillary ring or inner orifice, and have their ends turned 



toward it; the inferior margin of this orifice is armed with a slightly 



curved dental piece, having five acute points or teeth (the outer being 



larger than the three middle) ; opijosite to it on the ux)per side of the 



orifice is another j^iece having two large, acutely conical teeth, with 



a smaller central one. The tongue is also clothed with a horny-looking 



substance, which is edged anteriorly by a row of about twenty fine 



teeth. The dorsal fins rise in even curves, which are highest in the 



middle; the first is about one third of its own length from the second. 



Back and sides bluish graj^, with irregularly scattered yellowish patches ; 



belly yellowish white. Size rather large. — [Richcvrdson.) Pacific coast 



of North America, ascending streams. 



(Pctromijcon ^rirfewta/Ms Gairduer,.MSS.; Eicliardson, F. B. A. 293: Petromyzon ciUa- 

 tus Ayres, Proc. Ciil. Ac. Sci. 1854, 44 : Pttromijzon ciUafus et lividus Grd. Pac. R. R. 

 Surv. 378,379:. Ichthyomijzon iridentatua Gthr. viii, 50o.) 



XX Lips \A-itliout fringes of papillae. 



5. Li. epiUBexodon (Gill) J. & G. — Six-toothed Lamprey. 



This species is said to differ from L. tridentata in the absence of a 

 fringe of jjapilhe around the buccal disk, and in the presence of six 

 instead of four teeth in the upper transverse row. — {Girard.)» Sacra- 

 mento Kjver. 



{Petromyzon tridentatus Gril. Pac. R. R. Surv. 377; not Eicli. : Entospliemis cpikcxodon 

 Gill, Proc. Ac. Nat. Bci. Pliila. 1862,33.) 



ft Maudibulary plate Avitb six clisps, wliicli are nearly equal in size. 



©. L,. aslOB-i (Grd.) J. «& G. 



Lips fringed; head C^ in length; first dorsal lower than the second, 

 separated from it. by a space nearly equal to a third of its length; no 

 anal fin; yellowish brown, darker above. — (Girard.) Astoria, Oregon. 



(PciromyzonastoriGiravd, Pac. R. R. Surv. 380 : Ichthyomyzonasiori Giiuther, viii, 507.) 



** Maxillary plate bicuspid, tlie small median cusp wanting; mandibulary jilate with 

 about eight rather strong, subequal teeth. {Lampetra.) 



■y. ]L. plMBSatoea (Ayi^es) Gill. — Lead-colored Lamprey. 



Lips fringed; head 8 J in length; first dorsal much lower than the 

 second, and separated from it by a space equal to half of its own length; 

 tail tempering to a point; a single bicuspid tooth on each side of the ori- 

 fice of tiie mouth. Pacific coast; a small species, scarcely distinguish- 

 able froni the European L. fiuviatills. 



(Petromyzon pluml)eus Ayres, Proc. Gal. Ac. Nat. Sci. 1854, 28: Petromyzon ayresi 

 GUttther, yiii, 505 { dmmococtes cibarius Gu'ard, Pac. R. R. Surw 383.) 



