210 SILTJRID^E. 



serrated. The upper and lower surfaces of the tail are shielded 

 behind the adipose and anal fins. Humeral process s'triated, sword- 

 shaped, broader than, and extending to the hinder fourth of, the 

 pectoral spine. Eye small, covered by a membrane, as distant from 

 the end of the snout as from the gill-opening. The barbels are free, 

 not united at the base, provided with very small tentacles ; those of 

 the maxillaries do not extend to the gill-opening. Teeth very small, 

 present in both jaws. Dorsal and caudal fins with dark spots. (Kner.) 

 llio de la Plata. 



83. SYNODONTIS. 



Synodontis, Cur. 8f Val. xv. p. :!44. 



Brachysynodontis, Synodontis, Pseudosynodontis, Ilemisynodontis, 

 Leiosynodontis, Bleek. Nederl. Tydschr. ZHerk. 1803, p. 52. 



Adipose fin of moderate length, or rather long ; dorsal with a strong- 

 spine and with seven soft rays ; anal rather short. Teeth in the 

 lower jaw moveable, very thin at the base, and with a slightly dilated, 

 pointed, brown apex ; palate edentulous. Mouth small, mandibles 

 short. Barbels six, more or less fringed with a membrane or with 

 filaments. Eyes of moderate size. Neck with broad dermal bones. 

 The gill-openings are of moderate width. Yentrals with seven rays, 

 inserted behind the dorsal. 



Tropical Africa. 



Knowing most of the species of Synodontis from autopsy, I cannot 

 adopt the views of Dr. Bleeker, who has split this natural generic 

 group into five divisions : — 



a. /Synodontis has been 'estricted by him to a species with long, 

 slender intermaxillary teeth and with ciliated maxillary barbels (S. 

 macrodon). The discovery of a new species (S. sorex) already shows 

 that the characters used for the foundation of this genus are unser- 

 viceable : either it must lose one of the characters on which it is 

 based, or S. sorex would become the type of a sixth genus. 



b. Pseudosynodontis is created for S. serratrus, a species most 

 closely allied to S. scJud, which, however, is referred to Hi-misyno- 

 dontis. Although I am fully convinced of the distinctness of the 

 two species, I confess that, seeing the great variations in the develop- 

 ment of the spine of S. schal, I at first entertained some doubts about 

 it, nor did I feel satisfied on this point until I had ascertained by 

 dissection that the one was not the male sex of the other. If these 

 be considered types of two genera, then we may similarly separate 

 the short- and long-snouted Eels of our rivers. 



c. Ilemisynodontis is created for S. membranaceus, S. schal, and S. 

 nigritus. According to Dr. Bleeker's views, this is an assemblage 

 of most heterogeneous fishes, — the S. membranaceus differing from 

 the others by a great extent of the gill-opening, and by a structure 

 of the maxillary barbels, which is at least of as much importance as 

 the " cirri Ji-mbriati" of Synodontis, Blkr. 



d. Leiosynodontis is founded on S. maculosus, the young of Hemi- 

 svnodontis schal. 



