406 On a supposed New Species of Hippopotamus. 



is placed at the extremity of the lamelliform dental plate. The 

 palleal impression is distinctly marked, and extends parallel with 

 the margin of the shell, from the anterior to the posterior muscu- 

 lar imprint. The prevailing tint of the shells is a reddish taw- 

 ny color ; when recent they must therefore have closely resem- 

 bled some of the richly colored species of the Ohio. The weight 

 of a pair of shells, cleared of the stone, is eleven ounces avoir- 

 dupois. 



This interesting addition to the fauna of the Wealden, tends 

 to confirm the opinion I first advanced in my Illustrations of the 

 Geology of Sussex, namely, that a great proportion of the strata 

 comprehended in that formation, was deposited in the bed of a 

 vast river which flowed through a country inhabited by colossal 

 reptiles, and clothed with forests of palms, ferns, and coniferous 

 trees. 



With great regard, my dear friend, yours most faithfully, 



Gideon Algernon Mantell. 



Art. XVIII. — On a supposed New Species of Hippopotamus ; 

 by S. G. Morton, M. D.* 



It is about six months since I received from my friend Dr. 

 Goheen an extensive series of skulls, of mammiferous and other 

 animals, from Western Africa. They had been obtained by him 

 during a residence of several years at Monrovia, where he had 

 officiated as colonial physician ; a situation which gave him 

 great advantages for procuring the natural productions of that 

 region. Among these crania were two of a Hippopotamus, of 

 small size, from the river St. Paul's. Although nothing could 

 be more manifest than the difference between the head of this 

 animal and that of the common species, I have hesitated to pub- 

 lish it, from a fear that some one else may already have done so ; 

 for I could hardly convince myself that so remarkable a species 

 was wholly unnoticed in the systems. Having, however, search- 

 ed the latest European works on zoology without finding any ac- 

 count of this interesting animal, I venture to submit the follow- 

 ing facts in relation to it. 



* From the Proceedings of the Acad. Nat. Sci. Phil. Feb. 1844. 



