214 



U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



limb is also more slender. The head is more elongated, more conical than in M. lateralis, and 

 larger than in H. f rater culus. The mouth is larger than in either of the fcwo species just alluded 

 to. The fins are well developed ; the dorsal and anal both are deeper than long ; their formula 

 reads : 



D 2, 8 + 1 ; A 2, 8 + 1 ; 8, 1, 9, 8, 1, 7 ; V 1, 9 ; P 17. 



The scales are sub-elliptical, somewhat smaller on the abdominal region than on the dorsal 

 region. 



References to the figures. Plate XL VI, fig. 1, represents Mylocheilus caurinus, size of life. 

 Fig. 2, a scale from the dorsal region. Fig. 3, a scale from the lateral line. Fig. 4, a scale 



from the abdominal region. 



List of specimens. 



2. MYLOCHEILUS LATERALIS, Agass. & Pick. 

 PLATE XLV, FIGS. 58. 



SPEC. CHAR. Head constituting the fifth of the total length. Snout sub-conical. Posterior extremity of the maxillary 

 extending to a vertical line drawn across the hind nostril. Diameter of the eye entering five times and a half in the length of 

 the side of the head. Anterior margin of dorsal fin equi-distant between the extremity of the snout and the insertion of the 

 caudal. Base of anal fin contained fourteen times in the total length. 



SYN. Mylocheilus laleralis, AGASS. & PICK, in Amer. Journ. of Sc. 2d ser. XIX, 1855, 231. GRD. in Proc. Acad. Nat. Sc. 

 Philad. VIII, 1856, 169. 



Although the dorsal and anal are both deeper than long, the length of the latter is propor 

 tionally less than in the preceding and the following species. The fins present the general 

 aspect, with a few differences in the number of the rays : 



D 1, 8 + 1 ; A 1, 9 ; C 8, 1, 9, 8, 1, 9 ; V 1, 10 ; P 19. 



The scales exhibit, also, the same general characters ; their anterior margin, however, ap 

 pears to be more irregular ; hence their outline assumes a somewhat less elliptical form. 



References to the figures. Plate XLV, fig. 5, represents Mylocheilus lateralis, size of life. Fig. 

 6, a scale from the dorsal region. Fig. 7, a scale from the lateral line. Fig. 8, a scale from 

 the abdominal region. 



List of specimens. 



