59. ARius. 149 



of the head (its own length included), and twice and a half as broad 

 as long. The basal bone of the dorsal spine is quadrangular, slightly 

 narrowed in the middle. (VaL) 

 Surinam ; Porto llico. 



17. Arius passany. 



Bagrus passany, Cuv. Sf Veil. xiv. p. 458. 



D. 1/7. A. 17. 



Similar to A. proojjs. 



The eye is close to the end of the snout and remote from the prae- 

 opercular limb ; the lower jaw is the longer. Teeth on the palate 

 and barbels similar to those in A. proops ; occipital process shorter 

 than in that species ; basal bone of the dorsal spine subcrescentic. 

 Ventrals longer than pectorals. ( Val.) 



Cayenne. 



18. Arius caerulescens. 

 D. 1/7. A. 17. P. 1/10. 



The height of the body is contained about five times in the total 

 length (without caudal), the length of the head thrice and a half or 

 thrice and two-thirds ; head much broader than high, its greatest 

 width being three-foiu'ths of its length. Eyes rather small, their 

 diameter being one-half of the extent of the snout, two-sevenths of 

 their distance from the gill-opening, and one-third of the width of 

 the Lnterorbital space. The teeth on the palate 

 form a slightly cuiwed band, composed of two 

 vomerine patches which are much broader than 

 long, and of a pair of palatine patches Avhich 

 are subcontinuous with, scarcely broader and 

 longer than, those of the vomer. The bar- 

 bels of the maxiUaries extend to the middle, the outer ones of the 

 mandible to the base of the pectoral. Crown of the head granular ; 

 occipital process broader than long, subtri- 

 angular, subtruncated behind, and slightly 

 raised along the median line ; the basal bone 

 of the dorsal spine is subtriangular, small. 

 Dorsal spine of moderate strength, more than 

 half as long as the head, granulated in front 

 and slightly serrated behind ; the first soft ray 

 is as high as the body. Adipose fin shorter 

 than the dorsal. Caudal deeply forked, with 

 the upper lobe longest, its length being nearly — - 



equal to that of tlie head. Pectoral spine serrated along its inner 

 edge and on the extremity of its outer edge ; it is as long as the 

 head without snout. Ventral fin shorter than pectoral. Sides steel- 

 blue, iridescent, blackish towards the back, and silveiy below. Ver- 

 tical fins black ; inner side of the paired fins blackish. 



Guatemala. 

 u-h. Fine specimens, 12 inches long. Huamuchal. From the Col- 

 lection of Messrs. (Jodman and Salvin. 



