86 SILUROIDS. 



In the genus Acanthicus,{l) the maxillary teeth are bisinflected ; 

 the first, or anterior tooth of each of the radiating rows, is the 

 shortest, and is curved outwards, the rest, to the number of seven 

 or eight, being bent backwards : there are from twenty-five to thirty 

 of these rows on each side of both upper and lower jaws. 



The setaceous teeth of the Rhinelepis{2) have a similar arrange- 

 ment in antero-posterior radiated rows, and a similar moveable connec- 

 tion with the maxillary membranes ; but the foremost tooth in each 

 row has its inflected summit split, and thus presents the singular form 

 of a bicuspid hook ; the posterior succeeding teeth, in each row, have 

 a simple hooked apex. 



The foremost tooth of each radiated series in the Hypostoma{3) 

 is much shorter than the second, and is bent outwards : the second, 

 third and fourth teeth, counting backwards, are twice curved, with 

 the apex bent inwards ; the succeeding teeth grow shorter, present a 

 simple curve, and thus gradually disappear. 



In the Loricaria the bisinflected setaceous teeth are arranged in a 

 simple series along the alveolar border of the intermaxillary and pre- 

 mandibular bones : the summit of each tooth is curved inwards and 

 backwards. 



From the constancy observed in the different sizes, shapes and 

 directions of the teeth composing the vertical or radiated rows in 

 the above genera, it is to be inferred that they do not succeed each 

 other, and are not on the constant move from behind forwards, 

 as in the Plagiostomous fishes, with which in other respects the 

 teeth of the Goniodonts offer some striking analogies. 



SILUKOIDS. 



33. The dental armature of this extensive and singular family of 

 fresh-water fishes is never of a predatory or formidable character, 

 the teeth being always small and simple, or of a minutely villiform 

 kind. Some species are almost edentulous, but there are others 

 which exhibit peculiar conditions of the teeth not elsewhere ob- 

 servable in the vertebrate division of animals. 



In the genus Cetopsis a single series of simple conical teeth 



(1) PI. 48, fig. 3, (2) lb. fig. 2. (3) lb. fig. 1. 



