NOTE TO THE MEMOIR ON MOSASAURUS AND THREE ALLIED NEW GENERA. 13 



NOTE. 



Since the preceding paper was placed in the hands of the commission, I 

 find in the February number for 1850 of the Quarterly Journal of the Geologi- 

 cal Society of London some interesting notes of Prof Owen "Ora remains of 

 Fossil Reptiles discovered by Prof. H. D. Rogers in Greensand formations of 

 JYew Jersey^ He mentions the loss of a paper which he had read before the 

 Geological Society giving a more particular account of these fossils, but gives 

 the general results of his investigations. 



The examination of Prof Rogers's specimens of vertebrae led Prof Owen to 

 notice a division of those which were Crocodilian into two series, based upon a 

 character of the kypapopkysis. In the one it is single, and in the other cleft. 

 Other characters induce him to consider the vertebrse in question as belonging 

 to the "oldest of the modern Crocodihan family." 



For that distinguished by the single hypapophysis, he proposes the specific 

 name of C. basitruncatus ; while for the cleft apophysis he adopts that of C. 

 basifissus. These vertebrae are identical with several in the cabinet of the 

 Academy of Natural Sciences of Philadelphia, which have been described by 

 Prof Agassiz in the proceedings of the Academy of National Sciences, on 

 which he founds two new genera, Spkenosaurus and Bottosaurus. Of Mosa- 

 sauroid vertebrae, Prof Owen describes and figures some of the same type as 

 those of Mosasaurus, but "longer and more slender" — thinks they may belong 

 to Leiodon^ but in the absence of confirmatory evidence prefers to refer them to 

 a new genus, '•'■Macrosaurus.''^ The figures resemble precisely the vertebrae of 

 those of a fine specimen discovered by Prof Tuomey in Alabama, now in the 

 care of Prof Agassiz for description. As the maxillary bones and teeth are in 

 good preservation, we may anticipate much valuable addition to our stock of 

 knowledge of this family of Saurians. 



Prof Owen also gives figures of other vertebrae characterized by the large 

 size, and especially the great antero-posterior extent of the hypapophysis, and 

 the concavity of the articulating faces resembling those of the Teleosauroids. 

 These he considers as constituting a new genus, which he calls Hyposaurus., 

 and dedicates it to our eminent Geologist, Prof H. D. Rogers. 



I had hopes, before the addition of this note, to have had the opportunity of 

 examining the collection of Prof Rogers, but the box containing the specimens 

 was accidentally mislaid, and has not yet reached me. 



Kov. 1, 1850. 



