252 DESCRIPTION OF YERTEBRATE REMAINS, CHIEFLY 



The tooth of figure 36 has the crown proportionately larger and the root 

 thicker but narrower, and with but feebly developed processes. 



Length of the tooth, 6 lines; length of the crown, 2 lines; breadth at base, 

 31 lines- length of crown at middle, 4^ lines; breadth, 4 lines; thickness, 3 lines. 



XIPHODOLAMIA.* 



XiPHODOLAMIA ENSIS. 



While eno-aged in describing some unusual forms of the teeth of Sharks, I 

 take the opportunity of noticing another from the marls of New Jersey. The 

 teeth to which I refer are probably symphysial, but their relationship with lateral 

 associates remains undetermined. The museum of the Academy contains twelve of 

 these teeth, of which six are from Vincenttown, presented by Col. T. M. Bryan ; 

 four from Monmouth Co., presented by Dr. P. Knieskern ; one from Burlington 

 Co., presented by Dr. C. C. Abbott ; and one from Allowaystown, presented by 

 Dr. H. C. Yarrow. The teeth have the general appearance of those of Lamna 



laterally compressed. 



The crown of the tooth usually, as represented in figures 25-28, Plate xxxiv., 

 has a sigmoid sabre-like form with the anterior border sharp and the posterior 

 border obtuse. The root has the construction of that of a Lamna tooth, but the 

 two sides appear pressed towards each other, so that the processes are directed 

 obliquely and parallel. In some teeth, as in figure 27, the processes are nearly or 

 quite equal ; in other teeth, as in figures 25, 26, one process is shorter than the 



other. 



Fi«-ures 29 and 30 represent transitional forms from that above indicated to 

 the more ordinary one of Lamna teeth. In one of these, fig. 29, the crown is 

 sharp a short distance below the point on the outer border, as it is the entire 

 length along the inner border ; in that of fig. 30 the crown is sharp along both 

 borders. The root in both teeth is not laterally compressed, but has nearly the 

 common form seen in most teeth of Sharks. 



PRISTIS. 



Pbistis ensidens. 

 Leidy: Proceedings Academy of Natural Sciences, Philadelphia, 1855, 414. 



Multitudes of isolated teeth of several species of Saw-fish have been found in 

 the Ashley phosphate beds. From among a number of specimens in the museum 



* Contracted from Xiphodontolamia. 



