M. Talbot — Podokesaurus holyokensis. 475 



be a gastrolith. This would seemingly be the first record of 

 gastroliths found with carnivorous dinosaurian remains. 



Comparison with other for wis. 



Herbivorous dinosaurs. — Compared with Nanosaurus agi- 

 lis Marsh, the oldest known predentate dinosaur, the following 

 points may be noted :* Points of similarity — The femur is 

 shorter than the tibia, the ribs are very delicate, and the poste- 

 rior extension of the ilium seems to have the same position. 

 Points of dissimilarity — In this form the femur is more slen- 

 der and is nearly straight, while in JVanosaurus it is distinctly 

 curved. In this form, too, the fourth trochanter is much nearer 

 the distal end of the femur, the metatarsals are more slender 

 and probably longer, the humerus is relatively much smaller, 

 the shaft of the ischium is narrower, the pubis has a long ante- 

 rior extension, and there is no postpubis. 



In Laosaurus consors Marsh,f from the Jurassic, the femur 

 is much curved and is more nearly equal in length to the tibia, 

 while the fourth trochanter is far up toward the proximal end ; 

 the fibula is more bent, curving away from the tibia ; the 

 metatarsals are very much shorter ; the prepubis is short and 

 pointed ; and a postpubis is present. Laosaurus has a short 

 humerus as this form has but the shape is not the same. 



Hypsilophodon foxii Huxley (fig. 5), of the Wealden, Eng- 

 land. Here we notice that the main points of difference are 

 in the length and position of the pubis, and the presence of a 

 postpubis in Hypsilophodon. In Hypsilojohodon the femur is 

 curved, but the fourth trochanter is situated more nearly as this 

 one is, toward the distal end ; the humerus is stouter and 

 larger in every way with the radial crest much farther from the 

 proximal end ; the metatarsals are much shorter ; the ribs are 

 very much stronger ; the neural spines are of an entirely dif- 

 ferent shape. 



Carnivorous dinosaurs. — Anchisaurus colurus Marsh,:}: a 

 very slender, long-limbed carnivore from the same Connecti- 

 cut valley Triassic, with which this form seems to compare 

 quite closely in general outline, shows the following differences. 

 There is a decided difference in the relative lengths of the 

 femur and tibia, the femur of the large form being much 

 longer than the tibia. Marsh points out that the long femur 

 is found in the larger animals of both carnivorous and herbivo- 

 rous types, while the smaller birdlike forms of both types have 

 the tibia longer than the femur.§ This small form certainly 



* Neubeschreibung des Originals von Nanosaurus agilis Marsh, F. von 

 Huene and E. S. Lull, fig. 1, p. 135. 



f Dinosaurs of North America, O. C. Marsh, pi. lvii. 

 i Ibid., pi. iv. §Ibid., p. 201. 



