•Cope.] 450 [Sept. 15, 



wards posteriorly. It contains six longitudinal rows opposite the ante- 

 penultimate dentary tooth. 



All the bony surfaces are smooth. 



Measurements. M. 



Length of mandibular ramus (straight) 162 



" symphysis of do. (straight) , 038 



" external dental series 077 



Width of ramus at dental pavement 040 



" skull at ends of 00. quadrata 138 



" extremity of O. quadra turn 024 



' " occipital condyle 018 



Length of superior dental pavement 065 



Width of basisphenoid posteriorly 029 



The supposed axis vertebra is longer than wide, and the centrum is 

 deeply excavated posteriorly. Anteriorly it appears to have lost a piece — 

 the centrum of the atlas, which, while fitting it closely, was not co-ossified 

 with it. There is a fiat horizontal convex ala in the place of a diapophysis, 

 and an obtuse median hypapophysial angle. The neural spine is compressed, 

 except posteriorly, where it is transversely expanded, terminating above 

 in a short obtusely accuminate apex. From this apex an obtuse rib passes 

 down the median line, and disappears above the neural arch, where the 

 spine is somewhat narrower. The postzygapophyses are well developed 

 And look downward. 



Measurements of axis. M. 



Length of centrum below 020 



Width, including diapophyses 035 



Elevation of spine from postzygpophysis 038 



Width of do., posteriorly 020 



Remarks. — This interesting form is probably allied to Pantylus, which 

 I have hitherto regarded as a Batrachian. The two genera may be placed 

 in a special family of the Pelycosauria, to be called the Edaphosauridce. 

 This family will be distinguished from the Clepsydropidce by the presence 

 of more than one series of teeth on parts of the jaws. It is possible that 

 Helodxctes must be placed in it. 



ECTOCYNODON Cope. 



Paleontological Bulletin No. 29, p. 508. 



A species now before me resembles in generic characters the type of this 

 genus, B. ordinatus. That species was described as having the canine 

 tooth near the middle of the maxillary bone, while in the present one it is 

 near the anterior part of it, as in some other genera. In the typical species, 

 as in the species to be described, the cranial bones are sculptured, and the 

 temporal fossse are. overroofed. The sculptured surface as well as the 

 canine teeth distinguish Ectocynodon from Pariotichus Cope and Proeo- 

 lophon Owen, which genera are otherwise related. 



