406 Synopsis of the Fresh Water Fishes, 



Hypostonius Robinii, Tal. 



Vernacular : Tata. 



Synonymy. 

 H. Robinii, Cuv. and Vol. Hist. Nat.des Poissons, vol. xv., p. 500, 1840. 



The body behind the head is slender, and has four longitudi- 

 nal carinas above, of which the two superior run along the row 

 of plates on each side of the dorsal, leaving the back between 

 them flattened ; of the remaining two, one runs on each side 

 along the centres of the second row of plates. Another carina 

 is formed by the angles of the fourth row, and is very distinct 

 anterior to the ventral, and obsolete behind it. 



The head from the muzzle to the nape is about two-ninths of 

 the entire length of the body, inclusive of the caudal ; but 

 excluding that lin, it bears a proportion to the body of one to 

 three and a fifth. The width of the head at the base of the 

 pectorals is considerably less than its length ; the anterior por- 

 tion of the interparietal is tumid, and from this tumidity a blunt 

 ridge proceeds backwards to the short, sub-acute termination 

 of the plates ; the plates above the eye are also tumid, and an 

 obsolete ridge is continued from each to the second lateral 

 carina from the back ; another rounded ridge advances from 

 the antero-superior border of the orbit to the anterior border of 

 the nostril ; a wide, rounded, central ridge also extends from 

 the muzzle to the space between the nostrils. The eyes are a 

 seventh of the length of the head, and separated from each 

 other by a space equal to three diameters ; the interval be- 

 tween them and the muzzle exceeds four diameters. 



D. I. 7—1. A. 1, 4. C. I. 6, 8, 1. P. I. 6. V. I. 5. 



Head with numerous round black spots. Dorsal purplish, 

 with two rows of black spots between the intervals of the rays ; 

 one of these rows is frequently obsolete, and sometimes the two 



