126 BULLETIN 110, UNITED STATES NATIONAL MUSEUM. 



elusion reached by him that they pertain to distinct genera, for teeth of both the 

 styles discussed are to be found in the jaws of a single individual. As stated else- 

 where in this paper, I do not believe that the teeth alone furnish diagnostic char- 

 acters that will serve to distinguish species or in most cases even genera of the 

 Theropoda. 



Now, a suggestion regarding the type of Labrosaurus ferox. The deep notch 

 in the edentulous part of the dentary and the decided bending down of the pos- 

 terior portion of the bone are features so entirely peculiar to anything known 

 among the Theropodous dinosauria, as to suggest that this dentary is abnormal 

 in these respects, and that it may have been produced through injury, though, to 

 be sure, the bone as now preserved shows no evidence of such malformation. 



Family COELURIDAE Marsh 1881. 



COELURUS? GRACILIS Marsh. 



Plate 36, fig. 4. 



Coelurus gracilis Marsh, Amer. Journ. Sci., ser. 3, vol. 35, 1888, p. 94. — Zittel, Handbuch der 

 Palaeontologie, Abt. 1, vol. 3,1890, p. 732.— Hay, Bull. No. 179, U. S. Geol. Survey, p. 493 — 

 Lull, Maryland Geological Survey, Lower Cretaceous, p. 1911, pp. 187, 188, pi. 15, fig. 1. 

 Type specimen. — No. 4973, U.S.N.M., consists of an ungual phalanx, lacking 

 the tip. Collected by J. B. Hatcher in 1887. 



Type locality. — Near Muirkirk, Prince Georges County, Maryland. 

 Horizon. — Arundel formation, Lower Cretaceous. 

 The original description is as follows : 



The smallest dinosaur found in these deposits is a very diminutive carnivore, apparently belonging 

 to the genus Coelurus. It was not more than one-half the size of the western species, and its proportions 

 were extremely slender. The bones are very light and hollow, the metapodials being much elongated 

 and their walls extremely thin. An ungual phalanx of the manus measures about 25 mm. in length, 

 and 14 mm. in vertical diameter at the base. This animal could not have been more than 5 or 6 feet 

 in length. 



Lull in 1911 recognized additional specimens pertaining to this species in 

 material in the Goucher College collection, Nos. 3336/ 3338, and 8176, consisting 

 of three teeth, the first two coming from the same locality as the type. 



The teeth resemble very closely that of Coelurus fragilis figured by Marsh; 2 but differ in the 

 total reduction of the crenulation of the anterior convex border, which is perfectly smooth in one of the 

 three specimens, has serrations of almost microscopical fineness for a short distance from the tip in the 

 second, while in the third specimen the border is broken away where the crenulation would occur if 

 present. The curvature of the teeth is similar in each species, while the variation in size may be ac- 

 counted for by a difference in the stage of growth of individual teeth; as it is, two of the Maryland ones 

 are slightly larger than the tooth of Coelurus fragilis figured by Marsh. 



The type specimen as shown in figure 4 [plate 36], lacks a considerable portion of the pointed 

 extremity. When compared with the unguals of the manus of Ornitholestes hermanni Osborn it 

 would appear to represent the ungual of digit III of the manus. 



i Now deposited as a loan in the United States National Museum. No. 3336 G. C.=8444, U.S.N.M.; No. 3338 G. C.=8445 

 U.S.N.M. No. 8176 not found when collection was transferred. 



2 Marsh, 16th Amer. Rept. U. S. Geol. Surv., pt. 1, 1896, pi. 7, fig. 1. Reproduced on plate 34, fig. 4. 



