PHENACODUS. 469 



Diameters superior p.m. ivj''°te™P°«'«™'^ '^O^^ 



M. 

 007 



transverse 008 



Diameters M. a ^ ^"te-'oposterior 008 



\ transverse 010 



Diameters M. iii «'i*''™P°«**^''"^ ^°^ 



c transverse 009 



Length of dental lino of mandible 076 



Length of base P-m. ii 0065 



Diameters P-m. iii 5 anteroposterior 008 



( transverse 004 



Diameters P-m. iv^^^t^ioPO^terior 009 



( transverse 0055 



Diameters M. i ^interoposterior 009 



( transverse 0066 



Diameters m. iii r^'"**''''?''^**"'"' 0^" 



i transverse 006 



Elevation of crovpn of inferior canine ■ 008 



Vertebrce. — The vertebral column is, probably, excepting the caudal 

 series, complete. The dorsals are disarranged anteriorly, and the median 

 lumbaTs are out of line, otherwise the centra are in place. There are seven 

 cervicals, fourteen dorsals, seven lumbars, and three sacrals. Eleven cau- 

 dals are preserved. 



The vertebrarterial canal is present on six of the cervical vertebrae. 

 Their centra are moderately elongate, and a little opisthocoelous. The ar- 

 ticular faces are oblique to the long axis, indicating the elevation at which, 

 the head was held above the body. They are all obtusely keeled below, 

 and the keel divides, forming a narrower or wider flat or concave triangular 

 area Avith tuberous angles. The atlas is the shortest of the cervicals, and 

 its neural arch is twice as wide anteroposteriorly as the inferior bar, and is 

 fiat except a double tuberosity on the anterior border. The latter, viewed 

 from above, is quite concave. The diaparapophyses are short, but wide 

 anteroposteriorly. They are more extended transversely in their posterior 

 half; their border contracts anteriorly, and the edge is a little wider. The 

 vertebrarterial canal pierces it above and within its posterior border, and 

 issues on the inferior face a little anterior to the middle. The artery notched 

 the anterior base of the diapophysis and then pierced the neural- arch on the 

 superior face equidistant between the diapophysis and the edge of the 

 cotylus. The facets for the axis are distinct below, and have a slight angle 

 on their internal edge. There is a small tuberculum atlantis with smooth 

 truncate face. Centrum smooth below. 



