83. syNonoNTis. 211 



e. Brachysynodontis is created for S. batensoda, Poipp., a synonym 

 of Hemisynodontis membranaceus, and founded on two characters, viz., 

 bipartite maxillary barbels and a slight denticulation of the end of 

 the operculum. The peculiarity of the former is nothing more than 

 the basal dilatation which may be seen in other Synodontes, and the 

 latter character disappears entirely in mature examples. 



We divide the species of this genus into the following divisions : — 



I. The gill-opening does not extend downwards beyond the root of the 



pectorals. 



A. Mandibulary teeth very slender, longer than the eye, p. 21 1. 



B. Mandibulary teeth not longer than the eye, p. 212. 



II. The gill-opening extends down wards to the throat, p. 215. 



I. The gill-opening does not extend downwards beyond the root of the 



pectorals. 

 A. Mandibulary teeth very slender, longer than the eye. 



1 Synodonti? sorex. 

 D. 1/7. A. 12. P. 1/9. V. 7. 



The gill-opening extends downwards to before the root of the 

 pectoral fin ; snout produced, pointed ; mandibulary teeth very long 

 and slender, as long as the eye, from six to eight in number. Maxil- 

 lary barbels half as long as the head, lined interiorly with a narrow 

 white membrane ; the outer mandibulary barbels two-thirds as long 

 as those of the maxillae, provided with filaments. The height of the 

 body is rather less than one-fourth of the total length (without cau- 

 dal), the length of the head two-sevenths. Dorsal and pectoral spines 

 slightly crenulated along their outer margins ; humeral process as 

 high as long. The first ray of the dorsal and pectoral fins produced. 

 The adipose fin commences at a short distance from the dorsal, its 

 'length being contained thrice and a third in the total (without cau- 

 dal). Caudal fin deeply forked, both lobes being prolonged ; the 

 upper is the longer, one-third, or more than one-third, of the total 

 length. Coloration uniform : a black band along each caudal lobe ; 

 a blackish spot at the base of the hinder half of the dorsal fin. 



Upper Nile. 

 a, b. Fine specimens (10 inches long). Chartoum. From Consul 

 Petherick's Collection. 



2. Synodontis macrodon. 



Silurus clarias, Hasselq. It. Pal. p. 369. 



callarias, part., Bl. Schn. p. 379. 



Pimelodus synodontis, Geoffr. Descr. Eg Poiss. pi. 12. figs. 5 & 6. 

 Synodontis macrodon, Is. Geoffr. Poiss. Nil, p. 156 ; Cuv . 8f Val. xv. 

 p. 252. 



&. 7 D. 1/7. A. 13. P. 1/8. * V. 7. 



The gill-opening extends downwards to before the root of the 



p2 



