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S1REN0IDEI. 



Family LEPIDOSIRENIDyE. 



Cranial roof-bones few ; no distinctly differentiated maxilla or 

 premaxilla, and no marginal series of teeth above or below ; jugular 

 plates absent. Caudal fin diphycercal. Scales cycloid. 



Genus CERATODUS, Agassiz. 



[Poiss. Foss. vol. iii. 1838, p. 129.] 



Syn. Hemictenodus, 0. Jaeliel, Sitzungsb. Ges. naturf. Freunde, 1890, 

 p. 7 (in part). 



Body elongate, laterally compressed, covered with very large thin 

 scales, superficially calcified ; head small and depressed, snout acute. 

 Notochord persistent. Dental plates above and below triangular or 

 irregularly ovoid in shape, with outwardly radiating, smooth ridges 



Fig. 40. 



Ceratodics forstcri, Kaffir.. — Open mouth, showing dentition: u, narial openings ; 

 x, vomerine teeth xx, palatine dental plates; xxx, mandibular dental 

 plates. 



forming a series of very large processes at the external margin, which 

 are sometimes feebly denticulated. Paired fins acutely lobate ; dor- 

 sal fin arising about the middle of the back, both this and the anal 

 fin being continuous with the caudal. 



This definition is given on the assumption that the early Mesozoic 

 teeth originally named by Agassiz pertain to a fish identical in 



