MARYLAND GEOLOGICAL SURVEY 43 



megalopliysum more nearly than that of any other species as far as 

 known. In the C. capelUnii Van Ben., according to the descriptions 

 and figures of Capillini, the frontal is more elongate and narrower on 

 the middle line and the tympanic bulla has not the posterior median 

 angle when viewed from below such as exists in the C. megalopliysum. 



" Comparison with the species described by Brandt from Eussia and 

 Italy, discloses numerous important differences.^ The frontoparietal 

 region in the C. priscum Br. is materially shorter than in the megalo- 

 phi/svm. The auricular bullae of C. prriscum, C. meyerii and C. Jclinderii 

 are gradually acuminate to an acute apex, when viewed from the inner 

 side, and are without the convexity of the lower side and the trunca- 

 tion of the apex characteristic of our species. The bulla of C. ratliJcei 

 is a little more like that of the Chesapeake form, but it is nevertheless 

 specifically distinct. It is, when viewed from above, broadly and sub- 

 equally rounded at both extremities, instead of being truncate at the 

 one and angulate at the other. The extremities are of subequal width, 

 while the anterior portion is much narrower in the C. megalopliysum. 



" Finally the bulla of the C. megalopliysum is of relatively larger size 

 than in any of the species noticed above. 



Measurements. 



m. 



Length of fragment below 565 



Width of fragment 515 



Width of glenoid region from bulla 150 



Length of glenoid from bulla (least) 100 



Width of sphenoid between foramina lacera 105 



Length of tympanic bulla below 100 



Width of tympanic bulla in front of external process 53 



Width of tympanic bulla behind external process 67 



Width at exoccipital processes 400 



Length anterior to parietals above 825 



Length of occipital from base of foramen magnum to 



apex (on curve) 290 



Width of occipital condyles and foramen 140 



' Memoires Acad. Imp. Sci , St. Petersburg, 1873, voL xx, p. 14o. 



