no. 1648. CERTAIN CARNIVOROUS DINOSAURS— HAY. 353 



The writer has likewise exposed the tooth which was displacing 

 the sixth functional tooth, the outer wall of whose base still remains. 

 The apex of the successional tooth is broken off. The long diameter 

 at the section thus furnished is 8.5 mm.; the short diameter, 5.5 mm. 

 The inner and outer faces are equally convex, both are smooth, and 

 both cutting edges are crenulated. 



Such being the structure of the teeth of the types of Ldbrosaurus 

 ferox and L. suleatus, it becomes evident that the two species belong 

 to quite distinct genera and almost certainly to different families; but 

 which of them belongs to Ldbrosaurus, if either, can be determined 

 only by future discoveries. 



In the lower jaw of L. ferox there were plainly 12 teeth. The first 

 was placed 03 mm. behind the tip of the jaw, between which and the 

 tooth there is a deep notch. The posterior part of the dentary is bent 

 downward in an extraordinary way, somewhat like that of a fringil- 

 line bird. These peculiarities show that this species belongs to a 

 family entirely distinct from that typified by Allosaurus. 



2. NOTE ON ANTRODEMUS LEIDY. 



In the writer's Bibliography and Catalogue of the Fossil Verte- 

 brata of North America, 1902, p. 489, all the species of Ldbrosaurus 

 are referred to Antrodemus Leidy. The responsibility of this assign- 

 ment must be shared by the writer and his friend, Frederic A. Lucas. 

 The writer is now inclined to recede from the position there taken. 



Antrodemus was established by Leidy" on the hinder half of a 

 caudal vertebra of some carnivorous dinosaur. This vertebra (Cat. 

 No. 218, U.S.X.M.) had been found by Dr. F. V. Hayden in Middle 

 Park, Colorado, and was supposed to have come from Cretaceous 

 deposits. Xow, inasmuch as no caudal vertebra 1 have been described 

 or even mentioned in connection with any of the species of Ldbro- 

 saurus, and inasmuch as it is very doubtful if Antrodemus vdlens 

 came from the same level as Ldbrosaurus lucaris, there appears to be 

 no sufficient reason for displacing Marsh's generic name in favor of 

 Antrodemus. 



By an inexplicable error the writer'' referred to Antrodemus the 

 remains described by Marsh as Allosaurus medius. These remains 

 had been found in Potomac deposits at Muirkirk. Maryland, and were 

 placed by Marsh in Allosmnms only provisionally. 



3. OX ALLOSAURUS MARSH AND CREOSAYTRUS .MARSH. 



The genus Creosaurus is a subject of discussion. Dr. S. W. "Willis- 

 ton c has called attention to the fact that a lumbar vertebra which 



a Proc. Acad. Nat. Sci. Phila., 1870, p. 3; Contrib. Ext. Vert. Fauna West. 

 Terrs., 1873, p. 207, pi. xv, fi.i;s. 10-1 8. 

 6 Bibliog. and Cat. Foss. Vert. N. Amer., p. 489. 

 c Amer. Jour. Sci., XI, 1901, p. 111. 

 Proc. N. M. vol. xxxv— 08 23 



