NATURAL SCIENCES OP PHILADELPHIA. 341 



This type is weaker and more slender than Lab^'rinthodon, and 

 the cranial scuta appear to be very thin. It is possible that this 

 part of the specimen ma}^ only be a cast, but I am not satisfied of 

 this. 



LEPTOPHRACTUS OBSOLETUS, Cope, spec. nov. 



The tubercles and ridges of the cranium are obtuse and low, and 

 the latter do not inosculate. An angular depression commences 

 at the middle of each lateral area and extends across the middle 

 line at the point of junction of the paired and single median scuta. 



The external surface of the dentary bone is marked with short 

 oblique grooves along its middle region ; above these are grooves 

 which inosculate, forming a figure like an open net dragged in the 

 long direction. Excepting the grooves the teeth are smooth. The 

 smaller ones are close togetlier, and their crowns are curved back- 

 wards ; the larger ones are at more remote intervals ; both have 

 enlarged bases ; whether both forms are in the same series I can- 

 not determine. There are from four to five of the smaller in an 

 inch. 



M. 



Depth of fragment of jaw (margin wanting) , . . .075 



Length smaller teeth 019 



" longer " 023 



Width of vertex at middle scuta 176 



" of paired median scuta 056 



" of single " 036 



Length of " " 048 



Some vertebrae were found at the same locality, but there is no 

 evidence as to the species to which they may have pertained. They 

 are short, concave on one end and probably so on the other. The 

 centrum of one is .012 in. in diameter; neural arches injured. 



The Leptophr actus was about as large as a medium sized 

 alligator. 



CONCHIOPSIS, Cope. 



This genus is represented by specimens of several species which 

 all agree in the structure of the scales. These resemble those of 

 the Gyropfychhis of McCoy, in having longitudinal curA^ed ridges, 

 which converge to the posterior margin round an imaginary axis. 

 A rather complete specimen which may be regarded as type, has 

 two dorsal fins and one anal; neither these nor the ventrals are 

 clearly lobate. The caudal fin is equally developed above and 



