MORPHOLOGICAL REVISION OF THE SUBORDER. 



95 



Tarsale iv is not present as a distinct element, the fifth metatarsal articulates 

 with a broad facet on the intermedium + ; there is little doubt that the distal portion 

 of this represents tarsale iv. 



Tarsale v is a small bone on the outer side of the intermedium and identified by 

 Cope as metatarsal 5. It carries a distinct saddle-shaped facet for the fifth metatarsal. 



^h& phalanges are represented by the proximal ends only. 



Fig. 26a. — Sketch restoration ot Clepsydrops natalis. About \'(>. Spines are restored except on the last 



three lumbar vertebrae. 



Measurements. — No. 41 lo. 



Length of lower jaw 121 



Width of anterior end of lower jaw 11 



widest part of posterior end 39 



Length of tooth line in upper jaw 86 



large maxillary tooth 14 



largest incisor 8 



maxillary next posterior to the large 



maxillary 9 



three posterior dorsals 43 



bottom line of anterior lumbar 13 



bottom line of posterior lumbar .... 11 



Length of first caudal 14 



scapula, from distal end to center of 



articular face 105 



Width of distal end of scapula 30 



Length of humerus 82 



Width of proximal end of humerus 33 



distal end of humerus 42 



Length of pubo-ischiatic symphysis nearly com- 

 plete 126 



Height from symphysis to top of iliac crest .... 8g 



Length of femur 121 



The restoration of Clepsydrops natalis here given indicates the slender 

 proportions of the body and the very long tail. The spines are restored in 

 toto with the exception of the first three presacrals, which are preserved. It 

 is believed by the author that the spines on this form had not reached the 

 disproportionate length found in the genus Dimetrodon. 



Genus DIMETRODON Cope (seep. 43). 



Characteristic specimens: No. 41 16 Am. Mus.: The type, an incomplete skull. 

 No. 4008 Am. Mus.: Cotype, vertical column from axis to first caudal. No. 4040 

 Am. Mus.: A vertebral column with axis and several precaudals, sacrum and tail to 

 the ninth caudal. No. i University of Chicago : Pelvis, incomplete skull and 

 vertebral column, scapula and humerus, femur, tibia, and fibula. No. looi University 

 of Chicago : Nearly complete skull, anterior part of vertebral column, humeri, ulnae 

 bones, and front feet. No. 1003 University of Chicago : A complete front foot and 

 imperfect anterior limb bones. 



