202 LEA'S DESCRIPTION OF A FOSSIL SAURIAN. 



EXPLANATION OF PLATE XVII 



Clepsysaurus Pennsylvanicus, Lea. 



1. Parts of two Vertebrae, with Spinous Processes attached. 



2. A Centrum ; vertical view, showing its hour-glass form. 



3. Terminal extremity of Spinous Process. 



4. Antero-posterior view of a Spinous Process. 



EXPLANATION OF PLATE XVIII. 



Clepsysaurus Pennsylvanicus, Lea. 



1 . A part of a Bone, probably of the Fore Arm or Leg. 

 1 a. Transverse Section near the superior Part. 



1 b. Transverse Section of the inferior broken portion. 



1 c. Transverse section of the same at the middle. 



1 d. An oblique view of the superior fractured portion. 



2. An oblique view of a Centrum, with a portion of a second one. 



3. View of the Terminal Articular Cavity of a Centrum, broken on the left side. 



4. Vertical view of a broken Centrum, with a slight groove on its superior surface. 



5. Vertical view of three Centri, somewhat mutilated, in juxtaposition. 



EXPLANATION OF PLATE XIX. 



Clepsysaurus Pennsylvanicus, Lea. 



1. The proximal extremity of a Eib, the head being broken off, as well as a small portion of the neck. 



The tubercle is entire. The anterior and posterior faces are represented at 1 and 1 a. 



2. A Vertebra imbedded in the rock. The posterior face is presented. The centrum has been carried 



off, leaving only a fragment. The spinous and oblique processes are nearly perfect, but somewhat 

 bruised. The left transverse process is exposed. The canal is mutilated, and filled up with 

 the matrix of hard Limestone. 



3. Fragment of the inferior portions of a Tooth, with its minute serratures imbedded in the rock. 

 3 a. Two fragments of the superior portion of a Tooth, imbedded in the rock. 



3 b. The Tooth, reconstructed from the three fragments. 



3 c. Five transverse sections of the Tooth are correctly represented, and indicate the form of the faces 



of the fractured parts, passing from a gibbous to a circular transverse form. 

 3 d. The Serratures of the Teeth, magnified about four diameters. 



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