8 CONTKIBUTIONS TO NORTH AMERICAN ICilTHlOLOGY IV. 
sides of Uie maxillary ring or inner orifice, and have tlieir 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) opposite to it on the upper side of the 
orifice is another piece having two large, acutely conical teeth, with 
a smaller central one. The tongue is also clothed with a horny-lookiug 
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. 
Hack and sides bluish gray, with irregularly scattered yellowish i)atches ; 
belly yellowish white. Size rather large. — [Ilicliardson.) Pacific coast 
of North America, ascending streams. 
(PetromijzoH tndeiitatus Gairdner, MSS.; Richardson, F. B. A. 293: Peti’omijzon cilia- 
h<s Ayres, I’roc. Cal. Ac. Sci. 1854, 44: Petromyzoii ciliatua et Uvidus Grd. Pac. E. R. 
Siirv. 378,379: Ichihyomyzon tridentatus Gthr. viii, 503.) 
tt Lips withont fringes of paxiillaj. 
5. IL. cpilacxodoBa (Gill) J. & G. — Six-toothed Lamprey. 
This species is said to ditfer from L. tridentata in the absence of a 
fringe of papillie around the buccal disk, and in the presence of six 
instead of four teeth in the upper transverse row. — {Girard.) Sacra- 
mento Eiver. 
(Pctromyzon tridentatus Grd. Pac.^. R. Surv. 377; not Rich. : Entosphenus epihexodon 
Gill, Proc. Ac. Nat. Sci. Phila. 1862,33.) 
+t Mandibulary jdate with six cusi)s, which are nearly equal in size. 
6. Ij. astori (Grd.) J. & G. 
Lips fringed; head 6^ 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. 
{Pciromyzon astori Girard, Pac. R. R. Surv. 380 : Ichth yomyzon astori Gunther, viii, 507. ) 
** Maxillary i)late hicnsjiid, the small median cusp wanting; mandibulary jdate with 
about eight rather strong, subequal teeth. (Lampetra.) 
'7. S.. iJlMBSttBsea (Ayres) Gill. — Lead-colored Lamprey. 
Lips fringed; head in length; first dorsal much lower than the 
second, and separated from it by a space equal to half of its own length; 
tail tapering to a i)oint; a single bicuspid tooth on each side of the ori- 
fice of the mouth. Pacific coast; a small species, scarcely distinguish- 
able from the European L. fluviatilis. 
{Petromyzon plumheus Ayres, Proc. Cal. Ac. Nat. Sci. 1854, 28: Pciromyzon ayresi 
Giiuther, viii, 505: Ammoccetes cibarius Girard, Pac. R. R. Surv. 383.) 
