14 SYSTEMATIC PALEONTOLOGY 



Zarhachis but not to the extent reached in that genus. The articular 

 face of the lumbar was injured " but evidently has been as deep as wide 

 and perhaps nearly round. The median impression is punctiform and 

 remarkably strong. The profile of the inferior outline is concave and 

 constituted by an obtuse keel, on each side of which is a short longitu- 

 dinal depression. The diapophyses have been broken off but their 

 bases are both broad and deep, slightly filling the concavity of the 

 infero-lateral face. The supero-lateral face strongly concave in both 

 directions. 



Length centrum 39 lines (78 mm.) 



Length of basis of neurapophysis 28.5 lines (57 mm.) 



Length of basis of diapophysis 20 lines (40 mm.) 



Width neural canal 4 lines (8 mm.)" 



" Caudal has broad diapophyses and a band-like impression passing 

 in front of them, and converging at center of median line below; a 

 character seen in many of the species of the genus. The points of 

 attachment of the chevron bones are well marked; they entirely dis- 

 appear on the middle portion of the centrum. The articular face is 

 similar to that of the lumbar, but is a little broader than high. These 

 surfaces are everywhere concave and are not marked by any longitu- 

 dinal ridges. 



Total length 39 lines (78 mm.) 



Length basis neurapophysis 25 lines (50 mm.) 



Length basis diapophysis 24 lines (48 mm.) 



Width neural canal 2.G lines (5.2 mm.) 



Width articular face 25.5 lines (5.1 mm.) 



Depth articular face 21.3 lines (42.6 mm.) 



" This is probably the second of the genera in length, and the third 

 in bulk." 



Occurrence. — St. Maky's Foemation. Mouth of Patuxent river. 



Collection. — The location of the type specimen is unknown. It was 

 loaned to Cope by Tyson, then the State Agricultural Chemist of 

 Maryland. 



