Fossil Reptiles of New-Jerseij. 137 



presumed meaning, as the other surface is in contradistinction 

 called round and demi-conical, it differs somewhat from our fossil, 

 and this may hereafter serve for one of its specific distinctions. 

 We imagine however that it is only meant that one surface 

 forms a segment of a larger circle than the other, as in the 

 Monmouth fossil. In this supposition we are supported by all 

 the figures given of the teeth of Mosasaurus. 



There are no measurements of the teeth given either in the 

 work of Cuvier, nor in that of Faujas St. Fond,* by which a 

 comparison may be formed in regard to the relative size of 

 these animals. Our recollections of the Maestricht animal are 

 too vague to assist us in the determination of this point. Cuvier, 

 however, gives the depth of the lower maxillary at various 

 places, from which we should judge (assuming that the frag- 

 ment of jaw in our specimen is nearly complete) the Mon- 

 mouth animal to have been considerably larger than that of 

 Maestricht.f It only remains to state what must be evident 

 after perusing these observations, that the fossil tooth of Mon- 

 mouth agrees in no one particular vdth the characters assigned 

 to the Ichthyosaurus. It will, we trust, be equally evident that 

 the tooth in our Cabinet, noticed and figured by Mitchill, and 

 which has formed the subject of the preceding remarks, be- 

 longs to the genus Mosasaurus, hitherto the largest fossil rep- 

 tile discovered on this continent. 



''' Essai de Geologie ou Memoires pour servir a I'Histoire Naturelle 

 du Globe. Paris 1803. His large work entitled Histoire Naturelle de 

 la Montagne de St. Pierre de Maestricht is not in this city. 



t Dr. Harlan has noticed (Jour. Acad IV. 235. pi. xiv.) a fossil mine- 

 ralized tooth from marie pits near Woodbury, New-Jersey. From its 

 serrated edges, and concave internal surface, we are disposed to consider 

 it as sui generis, although allied in all probability to Mosasaurus, 



