74 SILURID^. 



cated in front, its greatest width being foiu--fifths of its length ; upper 

 jaw overlapping the lower. Nasal barbels slender, not so long as 

 the snout; the maxillary barbels extend to the end of the pectoral, 

 the outer ones of the mandible to the root of the pectoral. The teeth 

 on the palate form four narrow bands of nearly equal length, the 

 vomerine band being interiiipted in the middle and not continuous 

 ■vnth the palatine band. The upper surface of the head coarsely gra- 

 nulated, the granules being arranged in striae. Occipital process not 

 much larger than, and similar in shape to, the triang-ular basal bone 

 of the dorsal spine. Dorsal spine strong, sHghtly serrated along both 

 edges, more than half as long as the head. Adipose tin short, sub- 

 divided into rays only along its upper margin in young individuals ; 

 in old specimens the division into rays extends to the base of the fin, 

 and the first ray is changed into a hard, pimgent spine. Caudal 

 forked ; both lobes equal in length, or the lower rather longer. Pec- 

 toral spine as long as, but stronger than, that of the dorsal fin, serrated 

 along both edges, slightly exteriorly and strongly interiorly. Ventral 

 rather shorter than pectoral. Dark grey above, white below ; a 

 blackish blotch behind the gill- opening ; a broad blackish band along 

 each caudal lobe. 



The transformation of an adipose fin into one with rays and spines 

 in this fish is a very curious fact. I have no doubt that very young 

 specimens are provided with a fin without any indication of rays. 

 RiippeU, when he described the species from a young specimen (4^ 

 inches long), did not observe anything peculiar in its fins. CJarotes 

 JieiK/linii (Kner, 1. c. taf. 1 & 2, and Hyrtl, ibid. p. 371, and the latter 

 in Donkschr. Wien. Acad. 1859, xvi. p. 1) is certainly nothing but a 

 deformed specimen of the same species ; the arrangement of the gra- 

 nulated plates on the upper surface of the head, as represented by 

 Hyrtl on pi. 2, is exactly the same as in our adult specimen. 



The species appears to be peculiar to the Upper Nile, although 

 single specimens, like that described by EiippeU, may be carried 

 down towards the mouth of the river. 



a. Fine specimen, 16 inches long. Chartoum. From Consul Pethe- 

 rick's Collection. — The S2)ine of the adipose fin is completely 

 formed. 



h. Eight inches long. Chartoum. From Consul Petherick's Col- 

 lection. — One-half of the adipose fin is transformed into rays. 



c-d. Six and seven inches long. Chartoum. From Consul Pethe- 

 rick's Collection. — The division into rays is only visible on the 

 margin of the adipose fin. 



31. MACRONES*. 



Macrones, Dmneril, Ichthyol. Anal. p. 484. 



Hypselobagrus, Macrones, Hemibagrus, et Aspidobagi'us, Bleek. Ne- 

 derl. Tydschr. Dierk. 1863, p. 96. 



Adipose fin long, or of moderate length ; a short dorsal with a 

 * 1. Pimclodus menoda, Hcnti. Buck. p. 203. — Pimelodus corsida, H. B. Fish. 



