59. ARIUS. 



151 



extends scarcely to the end of the head. Head granidated above. 

 Occipital process very small and short, but joining the very large 

 nuchal plate, the hinder margin of' which is deeply concave. Dorsal 

 and pectoral spines strong, granulated, moderately serrated behind ; 

 adipose fin rather longer than dorsal. (Val.) 



Cayenne. 



22. Alius flavescens. 

 Bagrus flavescens, Cuv. fy Val. xiv. p. 462. 



B. 6. D. 1/7. A. 18. P. 1/11. 



The eye is much nearer to the end of the snout than to the prae- 

 opercular limb; upper jaw slightly the longei. The band of teeth 

 on the palate has its lateral portions ovate. The maxillary barbel 

 extends to, or beyond, the middle of the pectoral. Head granulated 

 above ; occipital process very small and short, but joining the large 

 nuchal plate, which is slightly concave behind. Dorsal and pectoral 

 spines strong, granulated, moderately serrated behind ; adipose fin 

 one-third shorter than anal. (Val.) 



Cayenne. 



23. Arius temminckii. 

 Bagrus temmiuckianus, Cuv. 8f Val. xiv. p. 4G3. 



B. 6. D. 1/6. A. 21. P. 1/11. 



The upper surface of the head rather reticulated than granulated ; 

 occipital bone scarcely produced, broadly rounded behind, with a 

 small notch in the middle, corresponding to the pointed nuchal plate. 

 Dorsal and pectoral spines granulated in front, and only a little ser- 

 rated behind. The dorsal fin is as high as the body ; adipose fin one- 

 third shorter than anal. The maxillary barbels extend on to the 

 end of the ventrals, the outer mandibulary barbels to the middle of 

 the pectoral. ( Val.) 



Cayenne. 



c. African species. 



24. Arius latiscutatus. 



D. 1/7. A. 15-17. P. 1/12. Vert.^. 



Head rather broad and depressed, coarsely granulated above ; the 

 occipital process is broader than 

 long, subtriangular, with the 

 lateral margins undulated and 

 with a median longitudinal 

 ridge ; the fonticulus On the 

 upper side of the head is very 

 narrow and tapering behind, ex- 

 tending to the base of the occi- 

 pital process. Basal bone of the 

 dorsal spine narrow, crescent- 

 shaped. The length of the head 

 is one-fourth of the total (with- 

 out caudal) ; the eye is twice as 

 distant from the end of the oper- 

 culum as from that of the snout : 



