AND THREE ALLIED NEW GENERA. 



MOSASAUROID GENERA. 



HOLCODUS, Nov. Gen. 



Among my specimens I have a tooth from Alabama given me by Mr. Joseph 

 Jones, of Columbia, South Carolina, and from the latter State another, differing 

 from any which have been described. They are solid, and resemble in their pyram- 

 idal form those of Mosasaurus Hoffmani, but are compressed antero-posteriorly, 

 the dividing ridges making the anterior and posterior surfaces equal, and they are 

 both convex. They are also acutely pointed. In Mosasaurus the outer surface 

 is a plane, or nearly so, and both have longitudinal narrow planes near the base. 

 In the position of the cutting edges they resemble Geosaurus as described by 

 Professor Owen, but the distinction of this genus, besides the position of the ridges 

 and greater breadth, consists in the edges being serrated. In Professor Agassiz's 

 specimen of Mosasaurus the edges are equally serrated, settling the point that 

 serratures are characters of young teeth of Mosasaurus. Soemmering conjectured 

 that Geosaurus was the young of Mosasaurus. This is only the case with what 

 was considered an American species of Geosaurus by Dr. Dekay.* The genus 

 Geosaurus belongs to formations of an older date than the Cretaceous. 



In the teeth under notice, on the outer half, are many planes almost grooves, and 

 also on the inner face, Avhich is peculiarly striated towards the base. It is evidently 

 nearly allied to Mosasaurus., and I consider it as forming one of the Mosasauroid 

 family. 



As the striated character is a structural distinction, the name of Holcodus "j" is 

 given to the genus, and that of acutidens to the species. 



On a recent visit to Professor S. S. Haldeman, of Pennsylvania, I found in his 

 cabinet a Avell-marked specimen of this new genus from the Cretaceous of New 

 Jersey, which he has kindly allowed me to figure, PI. III. Fig. 13. The speci- 

 men from the Cretaceous of Alabama is represented in PI. III. Figs. 6, 7, 8, and 

 9. The other, from the Eocene of Orangeburg, South Carolina, was only a frag- 

 ment, and has not been drawn. 



CONOSAURUS, Nov. Gen. 



I am indebted to Captain A. H. Bowman, of the United States Topographical 

 Engineers, for several teeth of an acrodont saurian found in the Eocene of Ashley 

 River, South Carolina. At first vicAV I supposed them to be pterygoid teeth of 

 Mosasaurus, but they are Avithout divisional ridges or cutting edges, and the 

 section is circular and not elliptical. They are conical, solid, sharp-pointed, slightly 



* Annals of the Lyceum of Natural History, New York, Vol. III. 

 t From oXkos, striatus. 

 VOL. II. ART. 5. — 2 



