REPTILIA: NAOSAURUS 77 



Edaphosaurus, known only from the skull, and I myself would be 

 inclined to this belief, were it not that the two known specimens of 

 Edaphosaurus are altogether too small to go even with the smallest 

 of the known specimens of Naosaurus. On the west side of Hog 

 Creek, near Seymour, Texas, I found, two years ago, a very perfectly 

 preserved specimen, consisting of the right femur, tibia, and fibula 

 and part of the astragalus, all in close articulation, bones unlike 

 anything hitherto known from Texas. I am much inclined to 

 think that 'they really belong with Naosaurus, though that con- 

 clusion is reached merely by exclusion. I give herewith figures 

 of these bones, ventral views, in contrast with like views of the 

 corresponding bones of Dimetrodon incisivus, made from an unusu- 

 ally perfect specimen from the Craddock bone-bed, all drawn to the 

 same scale. It will be observed that the femur is much more slender 

 than that of Dimetrodon, the digital fossa is deeper and longer, 

 the trochanter more prominent, the adductor ridge also more promi- 

 nent and continued half-way to the outer condyle, instead of end- 

 ing with the trochanteric eminence. The lower extremity is more 

 gradually dilated, though the distal articular surfaces are much 

 alike. The tibia and fibula are characterized by their remarkable 

 shortness and stoutness, so short and stout that, had they been 

 found isolated, they would have been referred to the Eryopidae or 

 Diadectidae. The fibula in contrast with that of Dimetrodon, 

 here for the first time figured, is very different, though having the 

 same general characters and articular surfaces; its shaft is very 

 stout and its lower end much expanded. The tibia has its ends 

 rather larger than those of Dimetrodon, while scarcely two-thirds 

 as long; its shaft is stouter. That the leg belongs to a zygocro- 

 taphic reptile I am assured because of its general resemblance 

 to that of Dimetrodon, but that the habits of the animal were 

 very unlike those of Dimetrodon is equally evident. However, 

 there is certain evidence of a still unnamed reptile from these beds, 

 found in the Craddock bone-bed, of large size, but with slender 

 jaws, and this leg may possibly belong with that form, which 

 will be described and figured later. Should the form prove new, 

 as it undoubtedly is if not Naosaurus, it may be known as Brachy- 

 cnemius dolicjtomerus g. s. nov. 



