ICHTHYOLOGY. 



9 





polymorphic species of the genus, and we have deemed it expedient to give figures and outlines 

 of the most prominent forms on Plate X, of the U. 8. R. R. Expl. and Surveys, as a more sure 

 guide to future researches. 



It is, therefore, difficult to take into account the form of the hody in a specific point of view. 

 Generally speaking, however, it is sub-circular or sub-elliptical ; the head being of but moderate 

 development compared to the other species, constituting the third of the length, the caudal fin 

 excluded. The snout is bluntly sub-conical. The mouth itself is proportionally large, obliquely 

 directed upwards. The posterior extremity of the maxillary extends to a vertical line inter- 

 secting the anterior rim of the pupil. The eye is of moderate development, circular in form ; its 

 diameter entering about four times in the length of the side of the head, or else a little less. 

 The edge of the preopercle is not crenated. The opercular appendage, on the other hand, is 

 very large when fully developed, reaching even abnormal proportions. The origin of the 

 dorsal fin is situated opposite the upper edge of the base of the pectoral fins ; its spinous portion 

 is of medium height, with its outline more or less arched, it being subjected to some variations ; 

 it is always lower than the soft portion. The caudal is moderately emarginated posteriorly. 

 The tip of the ventrals overlap the vent and reach the anterior margin of the anal. The external 

 soft ray becomes filamentous in the adult and then projects beyond the anterior margin of the 

 latter mentioned fin. The pectorals are rather broad, and their extremity does not extend as 

 far back as the tip of the ventrals. The posterior extremities of both dorsal and anal fins fall 

 evenly with the same vertical line. 



X 

 X 



(Elm creek.) 



Ill, 9 : 



7 



1,5; 



13. (R 



convexifrons 



The scales are of moderate development, sub-hemispherical, rounded posteriorly, superiorly, 

 and inferiorly, and truncated or sub-truncated anteriorly ; always deeper than long. The pec- 

 tinations are often carried away with the epidermis. 



The color is either blackish or reddish brown, lighter beneath than above. The sides of the 

 head exhibit bluish spots, which are sometimes confluent into irregular lines. The opercular 

 flap is margined by a narrow light filet, whilst a black spot is occasionally observed upon the 

 base of the soft portion of the dorsal fin posteriorly. 



Plate II, fig. 5, represents Pomotis fallax, size of life ; fig. G is a scale from the dorsal region; 

 fig. (T, a scale from the lateral line ; and fig. 8, a scale from the abdominal region. 



Plate III, fig. 9, represents, size of life, the variety which we have formerly described as a 

 species under the name of Pomotis convexifrons ; fig. 10 is a scale from the dorsal region ; fig. 

 11, a scale from the lateral line ; and fig. 12, a scale from the abdominal region. 



List of specimens. 



Catal. JNo.of 



No. 



457 



458 

 459 

 460 

 461 



spec 



2 



1 

 5 



6 

 5 



Age. 



Adult. 

 • .do.. 



Locality. 





Rio Cibolo, Texas 

 Elm Creek, Texas 





When col- Whence obtained 



lected . 



1851 



1851 



Young- Rio Salado, Texas 1851 





• .do.. 

 . .do. . 



i 



Live Oak creek, Texas. . 

 San Pedro creek, Texas.. 



1854 

 1854 



Orig'l 

 No. 



Col. J. D. Graham 



do 



do 



Major Emory 



do 



64 

 .-.9 



Nature of 

 specimen. 



Collected by 



Alcoholic. 



do 



do 



Jno. II. Clark 



do 



do 

 do 



do 



• 9 



Dr. C. B. Kennedy. 



do 



• • * 



9 



1 



