212 silueid^:. 



pectoral fin ; mandibulary teeth very long and slender, nearly as long 

 as the eye. Maxillary barbels about as long as the head, provided 

 with long fringes. Dorsal and pectoral spines serrated along both 

 edges ; humeral process not much longer than high. 



Nile. 

 a. Eight and a half inches long. Presented by Dr. E. Riippell. 



This specimen differs in some respects from those collected by 

 Geoffroy St.-Hilaire: the length of its dorsal spine is two-fifths of 

 the total (without caudal), whilst it is one-fourth in the specimens 

 collected by the French naturalist ; the caudal lobes also are con- 

 siderably longer. 



3. Synodontis serratus. 

 Riippell, Beschreib. neuer Nil-Jische, p. 8. taf. 2. 



D. 1/7. A. 12-13. P. 1/9. V. 7. 

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

 pectoral fin ; mandibulary teeth rather numerous; much shorter than 

 the eye, in a narrow band. Maxillary barbels longer than the head, 

 lined with a narrow membrane interiorly. Dorsal spine longer than 

 the head (in adult specimens), serrated along both edges. Humeral 

 process longer than high, pointed behind. Dorsal and pectoral 

 spines and the upper caudal lobe produced into filaments. Uniformly 

 coloured ; young dotted with brown. 



Upper Nile. 

 a, b, c. Adult (22 inches long) and young. Chartoum. From Consul 

 Petherick's Collection. 



B. Mandibulary teeth not longer than the eye. 



4. Synodontis schal. 



Sormini, Vmj. Eg. ii. p. 279. tab. 21. fig. 2. 



Silurus schall, Bl. Schn. p. 385. 



Pimelodus clarias, Geoffr. Descr. Eg. Poiss. pi. 13. figs. 3 & 4. 



Synodontis arabi, Cuv. fy Val. xv. p. 261 ; HyHl, Denkschr. Acad. Wiss. 



Wien, 1859, xvi. p. 16. 



schal, Hyrtl, I. c. 



maculosu8, Riippell, Beschreib. neuer Nil-Jische, p. 10. taf. 3. fig. 1 



(young). 



D.l/7. A. 12-13. P. 1/8. Y. 7. Vert. ££. 



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

 toral fin- mandibulary teeth rather numerous, much shorter than 

 the eye. in a narrow band. Maxillary barbels longer than the head, 

 not fringed. Pectoral spine stronger and rather longer than that of 

 the dorsal fin, the latter being not serrated in front, and not much 

 longer than the head. Humeral process much longer than high, 

 pointed behind. The distance between dorsal and adipose fins is 

 much less than the length of the base of the former. Old and half- 



