1887.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM- 375 



This Lampetra resembles X. phnnhea Ayres, but pJumlea lias tlie uiau- 

 dibulary plate with eight cusps iustead of uiue ; and instead of the four 

 bicuspid lateral teeth plumbea has three, the luediau oue distiuctly tri- 

 cuspid. In our best developed specimen of phimhca also, the lingual 

 teeth are pectinate, but the number of pectinations is comparatively 

 smaller than in the Mexican species, and the middle of the series is 

 furnished ^ith a conical lobe which is very greatly enlarged. This may 

 be a character of youth. 



Kostril on the top of the head and very slightly in front of the eye. 



The head is somewhat longer than the chest, its length contained 7^ 

 times in the total. The mouth is moderately large ; the lips with a 

 conspicuous fringe of papilhie. The dorsal fin is inserted about midway 

 of the total length. It is separated into two portions by an interspace 

 which is one-half as long as the snout. The greatest height of the 

 anterior portion is about equal to the length of the eye, which is about 

 one-fourth of the length of the snout. The second dorsal is longer than 

 the first, but very little higher, its greatest height being about one-third 

 of the length of the snout. In its posterior portion there is a deep 

 notch, but no separation from the portion which is continued around 

 the tail. The eye is rather small, about one-fourth as long as the snout 

 and sMght>y more than one-half of the width of the interorbital space. 

 The maxillary tooth has large cusps which are well separated ; no trace 

 of a median cusp. The mandibular plate is curved and has nine teeth, 

 those at the extremities being somewhat enlarged. Four lateral bicus- 

 pid teeth. Numerous small, recurved teeth around the margin of the 

 disk, in many rows anteriorly, but reduced to two rows, well separated, 

 posteriorly. The lingual teeth are distinctly pectinate; twenty lobes may 

 be counted with a glass. 



The general color is chestnut brown, somewhat lighter on the belly. 

 Basal portion of the second dorsal pale; the remaining portion some- 

 what like the body. 



