4 UNITED STATES AND MEXICAN BOUNDARY. 



The base of the first or spiny dorsal is longer than that of the first, but the fin itself is 



arched in its outline. The first and second spines are shorter than the third, 



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which is the highest, the remaining ones diminishing gradually posteriorly. The tenth spine, 

 by its position, belongs rather to the second than the first dorsal. The second dorsal is higher 

 than long, sub-trapezoid ; its upper edge being but slightly convex, and the posterior rays 

 almost as high as the anterior ones. The posterior 



mar 



sub-concave ; the fin itself is contained five times and a half in the total length. The origin 

 of the anal corresponds to a vertical line intersecting the anterior third of the second dorsal ; 

 its base extends a little further back than that of the latter, although the tips of the posterior 



rays of both fins are nearly even, the anal being not quite so deep as the second dorsal is high ; 

 its whole base, including the three small and slender spines at its anterior margin, is shorter 

 than that of the second dorsal. The origin of the ventrals corresponds to a vertical line drawn 

 immediately behind the base of the pectorals. The fins themselves are broad and short, since 

 their posterior extremity does not reach the vent which is situated a little way in advance of the 

 anterior margin of the anal fin, and under a vertical line drawn between the two dorsal fins* 

 The pectorals are of moderate development, not extending quite as far back as the ventrals. 



Br. VI: VI; DX, 13; A III, 11; C 4, 1, 8, 8, 1, 3; V I, 5; P 15. (Rio Cibolo.) 

 Br. VI: VI; D X, 13; A III, 12; C 4, 1, 9, 8, 1, 3; V I, 5; P 14. (Rio Blanco.) 

 The scales are of moderate development, sub- oblique, deeper than long, provided with 

 radiating grooves upon their anterior section only, and pectinated posteriorly. The pectinations 

 of the scales of the dorsal region are either obsolete or else deciduous, and easily removed with 

 the epidermis. As a whole the fish has a rather smooth appearance, 

 trout than a perch were it not for its anterior spiny dorsal fin. From twenty-nine to thirty 

 longitudinal rows of scales may he counted upon the line of greatest depth, nineteen below 

 and nine above the lateral line. The scales under the throat are quite reduced in size ; those 

 on the cheeks being nearly as large as on the opercle. Minute scales may be observed upon the 

 caudal fin to almost three-fourths of the length of its rays, and a few scattered ones upon 

 the base of the second dorsal. The lateral line itself, from the upper region of the gill covers, 

 is slightly arched upwards until under the second dorsal fin, hence runs nearly straightway 

 along the middle of the peduncle of the tail to the base of the caudal fin. 



reminding us mor 



more 



brown or black, whilst the inferior regions are whitish or yellowish, and unicolor. A lateral, 

 more or less interrupted, dark band may be traced from the black patch at the posterior margin 

 of the opercle, to the base of the caudal fin. Three obsolete streaks may be seen upon the 

 cheeks diverging from the orbit. The fins are unicolor, except the second dorsal, which exhibits 



two longitudinal bars upon its base ; the upper ones are greyish olive, the lower ones yellowish 

 olive. 



Plate I, fig. 1, represents Dioplites nuecensis, size of life ; fig. 2, is a scale from the dorsal 

 region ; fig. 3, a scale from the lateral line ; and, fig. 4, a scale from the abdominal region. 



