

166 PALAEONTOLOGY. 



of Sheppey. Some teeth from German miocene have been 

 referred to this genus ; but at this period, if not at the earlier 

 tertiary one, Pycnodus became extinct. 



Family IX. — Dapedid^e. 



Notochordal rhombo-ganoids, with front teeth conical or 

 bifurcate, back teeth obtuse, vertebral column and side 

 scales continued into the upper lobe of an almost sym- 

 metrical tail-fin. 



The pycnodont Tetragonolepis of Bronn being eliminated, 

 the lepidoid fishes, referred by Agassiz to that genus, con- 

 stitute in the present family the genus JEchmodus, Eg. 

 These are distinguished from the closely-resembling genus 

 Dapedius, by having the small anterior teeth conical and 

 single-pointed, instead of being bifurcate ; and although this 

 character is subject to occasional variations, nevertheless, on 

 taking a comprehensive view of these dapedioids, it seems 

 to have been sufficiently constant to warrant the continuance 

 of their separation into the unicuspid (JEchmodus) and bicuspid 

 (Dapedius) front-toothed genera. 



The type-genus, Dapedius, is a compressed deep-bodied 

 fish, with a single dorsal, and a single series of fin-fulcra ; the 

 front teeth are commonly notched. All the species are from 

 liassic strata. Amblyurus, with a similar form, and also 

 liassic, has a very narrow anal, and a wide mouth with small 

 pointed teeth. Semionotus and Pholidophorus are long-bodied 

 fishes, the species of which range from the lias upwards to 

 the Purbecks (Pholidophorus ornatus), and to the chalk (Semi- 

 onotus Bergeri). 



Family X. — LEPiDOTimE. 



Homocercal rhombo-ganoids, with obtuse teeth and well ossi- 

 fied vertebrae. 



