

76 



UNITED STATES AND MEXICAN BOUNDARY 



The posterior nostril is large and placed near the eye ; the anterior nostril, on the other hand, 

 is very small, situated near the apex of the snout, and exteriorly of which may he seen a short 

 membranous expansion just in advance of the upper lip. The teeth are small, conical, disposed 

 upon a narrow longitudinal band on both jaws and along the vomer also ; wider anteriorly than 

 posteriorly where it tapers away. The branchial apertures are small, vertical, situated in advance 

 of the insertion of the pectoral fins. The origin of the dorsal fin corresponds to the anterior third 

 of the total length ; the origin of the anal fin is placed somewhat anteriorly to the middle of the 

 entire length. The scales are narrow, elongated, and cellular in structure ; and, although imbedded 

 in the slrin, they are quite apparent to the naked eye. They are disposed upon small group with 

 their longitudinal diameter in every possible directions, giving the surface of the animal a check- 

 ered aspect. They extend over the base of the fins. The upper region is dark olive green; the 

 inferior region being dull yellow or light olive. The periphery of the caudal fin is black. 



Plate XL, fig. 1, represents Anguilla tyrannus, reduced from a specimen over two feet long. 

 Fig. 2 is a scale from the dorsal region ; fig. 3, a scale from the abdominal region. 



List of specimens. 



Catal. 

 No. 



No. of Sex and 



spec 



age 



Locality 



When col- 

 lected. 



Whence obtained. 



8f)7 

 858 

 fc59 



1 



4 

 5 



Adult. 



Young 



Mouth of Rio Grande del Norte (B. Bravo) .. 

 Matamoras, Mexico - 



do 



1853 

 1852 



Nature of 

 specimen. 



Major Emory | Alcoholic 



Lieutenant D. N. Couch 



do 



do 

 do 





NEOMURAENA, Girard, 



Gen. Char. — Neither pectoral nor ventral fins ; dorsal and anal fins low, uniting into a point posteriorly. Anterior maxillar 

 teeth largest. One series of vomerine teeth. Gill apertures lateral and sub-circular. 



NEOMURAENA NIGROMARGINATA, Grd. 



Plate XLI. 



Spec. Char. — Head rather slender and sub-conical ; body compressed and tapering into a point. The mouth is deeply cleft, 

 the jaws being equal, its gape nearly horizontal, and its angle extending considerably beyond the orbit. The maxillar teeth are 

 blender and acute, canine-like, larger anteriorly than posteriorly ; a series of short sub-conical ones may be observed upon the 

 middle of the vomer. The eyes are sub-elliptical and of moderate development, 



t 



The posterior nostrils, which are also the largest, are situated above the orbits on a line 

 drawn in advance of the pupil ; the anterior nostrils being tubular, situated near the apex of 

 the snout and directed forwards. Small mucous pores may be observed on the upper surface as 

 well as on the sides of the head. The dorsal fin commences anterior to the branchial apertures, 

 which are sub-circular and rather small. The vent is placed anterior to the middle of the total 

 length, where the anal fin is reduced to a mere membranous ridge. The scales are so minute 

 and imperceptible that the body appears as though perfectly smooth. The lateral line is like- 

 wise inconspicuous. 



The ground color is reddish brown, darker above than below, with whitish clots scattered all 

 over the body and fins ; the dorsal fin is black, margined with a series of black spots ; the anal 

 being entirely black or purplish black. 







i 



