MOCHOCUS. 



389 



and a half in the interorbital width. Barbels long and slender, the maxillary once and 

 a half to twice and one-fourth as long as the head, reaching the posterior third of the 

 pectoral spine, the base of the ventral, or a little beyond ; mandibular barbels shorter, 

 with a few slender simple branches. Occipito-nuchal shield as long as broad or longer 

 than broad, with short, rounded posterior processes. A long pointed humeral process. 

 Anterior dorsal fin with I 7 (rarely 8) rays, much nearer the end of the snout than the 

 root of the caudal fin ; the spine as long as or a little shorter than the head, finely 

 serrated in front ; second dorsal fin with 10 to 15 rays, preceded by a few fulcra-like 

 bony scutes, as long as or a little longer than its distance from the first. A series of 

 three or four small bony scutes, ankylosed to the interneural bones, on each side of the 

 soft part of the first dorsal fin. Anal fin with 9 or 10 rays. Pectoral spine as long as 

 or a little longer than that of the dorsal, finely serrated on its outer border, with 7 

 (young) to 14 very strong antrose serrse on its inner border, reaching the base of the 

 ventral fin or not quite so far. Ventral fin equally distant from the end of the snout 

 and from the root of the caudal fin, or a little nearer the former, not reaching the anal. 



Measurements (in millimetres). 



Total length (without caudal) 



Greatest depth 



Length of head 



Width of head 



Length of snout 



Diameter of eye 



Interorbital width 



Width of mouth 



Maxillary barbel 



Outer mandibular barbel 

 Inner mandibular barbel 



Length of dorsal spine 



„ pectoral spine . . . . 



1. 



2. 



3. 



4. 



5. 



58 



52 



43 



31 



24 



12 



12 



9 



6 



5 



13 



13 



11 



8 



7 



12 



12 



10 



H 



6 



5 



5 



4 



H 



2 



3 



3 



3 



2 



H 



4 



H 



4 



3 



o 



4 



H 



3 



3 



2 



27 



2Q 



25 



16 



10 



16 



14 



16 



10 



6 



10 



9 



10 



8 



4 



12 



11 



10 



8 



5 



13 



13 



11 



8 



H 



1, 5. Luxor. — Loat. 



2. Between Luxor and Assuan. — Loat. 



3. L. No.-— Loat. 



4. G-ondokoro.— Petherick. (Type of R. typus.) 



