22 SILFRIDiE. 



are half as long as those of the maxillary, which reach only to the giU- 

 opening. Vomerine teeth viUiform, forming a crescentic band. 



Nile. 



2. Heterobranchus intermedius. 

 B. 9. D. 39-41. A. 49-50. P. 1/10. Vert. 19/43. 



The length of the adipose fin is rather less than two-thirds of that 

 of the rayed dorsal; pectoral spine scarcely serrated. The nasal 

 barbels extend to, or beyond, the end of the occipital process, those 

 of the maxUlaries beyond the root of the ventral fin. Vomerine teeth 

 villifoiTQ, forming a crescent-shaped band, which, in its middle, is 

 much broader than that of the intermaxillaries, and has a short 

 median posterior process. Blacldsh above, whitish below. 



Otherwise very similar to the other species. 



Upper Nile. 

 a, h. Adult (15 inches long) and half-grown. Khartoum. From 

 Consul Petherick's Collection. 



c. Adult: skeleton. Khartoum. From Consul Petherick's Collection. 



d. Preparation of the branchial organs and intestines of specimen c. 



3. Heterobranchus tapeinopterus. 



Sleeker, Nat. Tydschr. Nederl. Incl. iii. p. 732 ; Prodr. Silur. p. 337; and 

 Atl. Ichth. Silur. p. 101. tab. 97. fig. 1. 



B. 8. D. 24-27. A. 49-51. 



The adipose fin is much lower, but rather longer, than the rayed 

 dorsal ; caudal united with adipose fin and with anal. The length of 

 the head is rather more than one-sixth of the total (without caudal). 

 Pectoral spine distinctly serrated. The nasal barbels extend to the 

 base of the pectoral, those of the maxiUaries to, or beyond, the ex- 

 tremity of that fin. (-S/.) 



Banka and Borneo, 

 rt. Young. From Dr. P. v. Bleeker's Collection. 



4. Heterobranchus longifllis. 



Cuv. ^ Val. XV. p. 394. pi. 447. 



B. 9-10. D. 29-31. A. 44-46. P. 1/10. 



The adipose fin commences immediately behind the dorsal and 

 terminates at the root of the caudal ; its length is equal to, or not 

 much less than, that of the rayed dorsal ; pectoral spine distinctly 

 serrated. The length of the anal fin is nearly one-third of the total 

 (without caudal). The nasal barbels extend to the base of the occi- 

 pital process, those of the maxiUaries to the root of the ventral fin ; 

 but they appear to be rather shorter in large specimens. Vomerine 

 teeth vLlliform, forming an arched band which is as broad as that of 

 the intermaxillaries. Blackish above, whitish below. 



Nile. 

 a. Young: 7 inches long. Nile. 



h. Young : not good state. Khartoum (rain-water pond). Presented 

 by Consul Pcthcrick. — Vernacular name, Gannoot. 



