No. l8.] TRIASSIC FISHES OF CONNECTICUT. 47 



decline. Derived in all probability from the ancient Palseoniscid 

 stock, and still retaining certain of its characteristics, these 

 genera represent an advance over primitive sturgeons in the di- 

 rection of the next higher suborder (Protospondyli), yet without 

 marking a definite transition to that group. The upper lobe of 

 the tail has become shortened, although still heterocercal ; and in 

 Dictyopyge at least the supports of the anal fin are recorded as 

 fewer in number than the apposed dermal rays. The family 

 is accompanied in the Trias by other Chondrosteans which be- 

 came eel-shaped (Belonorhynchidse) and died out during that 

 period. Still others, which gradually lost their scaly covering 

 and head bones (Chondrosteus) , continued to survive, and are 

 represented by the sturgeons of the present day. The relations 

 of this family are, therefore, with modem sturgeons rather than 

 with the two surviving genera of Protospondyli, Amia and 

 Lepidosteus. 



Genus Catopterus Redfield. 



(Syn. RedHeldius Hay.) 



Trunk elegantly fusiform, head relatively small, tail hemi- 

 heterocercal. External bones more or less ornamented with 

 ridges and tubercles of ganoine; no median series of cranial 

 roof-bones. Fins of moderate size, consisting of robust rays, 

 more or less enameled, and distally bifurcated; fulcra well de- 

 veloped, short and closely set. Dorsal and anal fins triangular, 

 the origin of the former behind that of the latter; caudal fin 

 forked. Scales large or of moderate size, nearly or quite 

 smooth, and serrated along their postero-inferior margin ; dorsal 

 ridge-scales not much enlarged. Teeth numerous, small, acutely 



conical. 



This genus appears to be restricted to the Atlantic Border 

 Trias of North America, although a supposed Catopterid genus, 

 named Perleidus by De-Alessandri, occurs in the Ladinian lime- 

 stone of Lombardy, and the still more closely related genus 

 Dictyopyge is of world-wide distribution. 



It is to be noted that remains of Catopterus are on the whole 

 less abundant than those of the accompanying genus Semionotus, 

 both in the Connecticut Valley area and in New Jersey, and as 

 a rule they are less well preserved. Nevertheless, the characters 



