TRANSACTIONS OF THE 



the present volume of these Transactions together with 

 some fossil teeth of the Shark. 



Further north in the same state, from a place called 

 Erie, in a limestone somewhat similar, but of a formation 

 which Mr Conrad considers to underlie the above named 

 rock, and of a less recent date, being equivalent to the 

 green sands of New Jersey, I had previously received, 

 through the politeness of Colonel Long, of the U. S. 

 Engineers, a fine specimen of the caudal vertebra of the 

 Mosasaurus or Maestricht Monitor, together with numer- 

 ous Shark's teeth, similar to those found in the New Jer- 

 sey green sand. 



All the bones are alike totally destitute of animal mat- 

 ter, and are entirely destroyed and reduced to muriate 

 of lime by the addition of weak muriatic acid; they differ 

 from the rock only in colour; the pores occasionally con- 

 tain casts of small marine shells. 



We take it for granted that all the bones obtained 

 from the same spot, and almost in contact with each other, 

 constitute portions of one species. The great disparity in 

 their proportions and size, presents a remarkable feature 

 in the structure of this animal; so much so, indeed, that 

 we were at first inclined to refer the large and small 

 vertebrsB to different species : and bearing in view the 

 form and structure of the teeth only, we should have been 

 inclined to rank the animal among the marine carnivor- 

 ous quadrupeds ; but a careful examination of other por- 

 tions of the skeleton, and especially of the lower jaw, 

 which is hollow^ forbids this arrangement, and appears 

 to force it to take its station among the Saurien order, as 

 a lost genus. 



We understand from Mr Conrad, that he was informed 

 by Mr Creagh, that on his first settlement in that por- 

 tion of the country, a train of vertebrsB belonging to this 

 animal, was observed on the surface of this rock, extend- 



* Vide ante p. 340 ; plate 13, fig. 2. 



