350 



SILUKLCLE. 



11. SYNODONTIS. 



Cuvier, Begne Anim. ii. p. 203 (1817) ; Giinther, Cat. Fish. v. p. 210 (1864) ; Vaillant, N. Arch. 



Mus. (3) vii. 1895, p. 233, and viii. 1896, p. 87 ; Boulenger, Poiss. Bass. Congo, p. 301 



(1901). 

 Brachysynodontis, Bleeker, Nederl. Tijdschr. Dierk. viii. 1863, p. 54. 

 Pseudosynodontis, Bleeker, t. c. p. 55. 

 ffemisynodontis, Bleeker, 1. c. 

 Leio synod ontis, Bleeker, 1. c. 



Body short or moderately elongate, more or less compressed. Dorsal fin short, 

 formed of a strong spine and 6 or 7 branched rays ; an adipose dorsal fin. Anal fin 

 short. Pectoral fin with a strong spine. Ventral fin with 7 rays, inserted behind 

 the vertical of the dorsal. A cephalo-nuchal bony shield, united to the clavicular 

 bones. Three pairs of barbels : maxillary and two mandibulars, the latter branched 

 or fringed. Nostrils widely separated from each other, the anterior tubular. Eye 

 lateral or superolateral, with free border. Mouth with more or less developed lips ; 

 a band or series of conical praemaxillary teeth ; movable, slender, more or less curved 

 teeth implanted in the lower lip, usually followed by small teeth on the lower jaw ; 

 palate toothless. Gill-membranes confluent with the skin of the isthmus. Air-bladder 

 large, free. 



This genus, represented by fifty-two species, is confined to Tropical Africa and the 

 Nile. Thirteen species are known from, the Nile system. 



The bony casque is formed by the union of the skull with the nuchal shield 

 produced by an expansion of the anterior interneural bones, and with the clavicular 

 bones, the clavicle forming what is called the humeral process. The 6 or 7 anterior 

 vertebrae are coalesced. The vertebrae number 30 to 44. I have counted the following 

 numbers in the skeletons of Nile species examined : — 



8. schall . 



8. front osus 



8. nigrita. 



8. serratus 



8. clarias ' 



8. batensoda 



8. membranaceus 



16 + 24 = 40 



16 + 24 = 40 



17 + 22 = 39 

 17 + 27 = 44 

 17 + 25 = 42 



14 + 24 = 38 



15 + 24 = 39 



The branchiostegal rays are 7 in number. 



The elongate intestinal canal with numerous convolutions and the feeble dentition 



