CHAPTER XV. 



THE MICROSAURIAN FAMILY STEGOPID^E, FROM THE COAL MEASURES OF OHIO. 



Family STEGOPID^E Moodie, 1909. 



MOODIE, Jour. Geol., xvn, No. i, 79, 1909. 



The chief family characters are the large lacrimal, unknown in other species 

 of Coal Measures Amphibia, the central position of the orbits, the general form of 

 the skull, and the peculiar, short, divaricate horns from the squamosal. If an inter- 

 temporal element is present in the skull, which is suggested as a possibility, the 

 family is further distinct. The type species is Stegops divaricata Cope from the 

 Linton, Ohio, Coal Measures. 



The group seems to be distinct and has no immediate allies, being confined to 

 the American Coal Measures. 



Genus STEGOPS Moodie, 1909. 

 MOODIE, Jour. Geol., xvn, 79, 1909. 



Type: Stegops divaricata Cope. 



This genus has been erected for the reception of the peculiar form described by 

 Cope as Ceraterpeton divaricatum, but there are good reasons why the form can not 

 be retained in the genus. The position of the orbits in Stegops (plate 25, fig. 3) is dif- 

 ferent from Ceraterpeton and the muzzle is rounded, not truncate as in the latter 

 form. The horns are of a different type and there is no indication of the tabulare 

 protuberance which is present in Ceraterpeton. The sculpturing of the cranial 

 elements is also distinctive in the present form, consisting of radiating grooves and 

 ridges; the cranium of Ceraterpeton appears to be but slightly sculptured. There 

 is no lateral projection from the border of the skull in Stegops, as there is in the 

 other genus. The structure of the skull of Ceraterpeton is practically unknown, 

 except in a very general way, although Andrews (8) was able to make out some of 

 the elements and to trace the lateral-line canals. A structural comparison is thus 

 impossible, but on the basis of form alone there are good generic distinctions. The 

 present genus is apparently distinct from other genera in the presence of an inter- 

 temporal, but additional material will be required before a satisfactory determina- 

 tion is possible. The genus Diceratosaurus of Jaekel (347) is distinct in the arrange- 

 ment of the elements of the cranium, the general form of the skull, and in the two 

 known species of Diceratosaurus the orbits are located well anteriorly, but in 

 Stegops they are in the median transverse line of the cranium. The genus Stegops is 

 distinct from Eoserpeton in the smaller size of the prosquamosal, in the broadly 

 rounded muzzle, in the larger and more posteriorly placed orbits, and in the pres- 

 ence of an intertemporal bone, or at least in the elongate character of the post- 

 orbital if the intertemporal is not present. The species on which the genus Eoserpe- 

 ton is based was first described by Cope as Ceraterpeton tenuicorne. The form is 



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