NOTES OX THE IDENTIFICATION OF CH.ETOGNATHA. 



71 



and slightly curved. This group includes Sagitta cnflata and S. 



fur cat a. 



Sagitta fw'cata (3 and 4). 



Base of point b and top of shaft / converge as they approach 

 the back of the shaft bk. Cross-section of the shaft is a slender 

 wedge-shape. Pulp p is displaced toward the back of the shaft 



/;/'. Pulp / is concentrated around a canal can, which is of a 

 cucumber form and extends to the upper third of the shaft. Old 

 jaws with a small crest. 



Sagitta e7iflata (5). 

 Base of point b and top of shaft /converge as they approach 

 the edge of the shaft eg. Edge of point eg.pt near the base b is 

 notched n. Cross-section of 

 the shaft more of an oval 

 than in S. fiircata. Canal ir- 

 regularly distributed through 

 the pulp. 



Group 3 (Figs. 6 and 7). 



Point pt with a broad oval 

 base b. Pulp p slightly 

 toward back of the shaft bk. 

 Base of point b makes a right 

 angle with the back of the shaft bk 

 point b and edge of shaft eg is acute, 

 short massive crest cr. Edge of crest extends proximally on a 

 line with the edge of the point for some distance and then makes 

 an abrupt turn toward the shaft. Shaft evenly and strongly 



Angle between base of 

 Shaft below point with a 



