Vol. 6$.~] A. NEW DINOSAUEIAN REPTILE. 143 



complete, and is always found in undisturbed contact with the 

 tibia. The tarsal bones are obscure in all cases, but they are 

 scattered in the second specimen, and one of them (PI. IX, rig. 4) 

 is remarkably similar to the elongated calcaneum discovered by 

 Marsh in Hallopus. The metatarsus (mt.), which is conspicuous 

 in all the fossils, is half as long as the tibia, and consists 

 of four slender elements, of approximately equal length, firmly 

 fixed together. At least, these four bones always lie in close contact 

 in perfectly-parallel order, however much the foot may be crushed 

 and displaced. On the outer side of the proximal end of the 

 metatarsus of the left hind-foot in the type-specimen, there is the 

 impression of a small bone which appears to be a rudimentary fifth 

 metatarsal, although it may be only a displaced tarsal. Three of the 

 proximal phalanges of the foot (p) occur well separated by matrix 

 in both Mr. Taylor's specimens, and the longest toe in the type- 

 specimen clearly comprises five phalanges, of which the terminal is 

 a pointed claw. 



There are no traces of dermal armour, but an impression of the 

 abdominal wall is distinctly preserved in the British-Museum 

 specimen (PI. IX, fig. 2), owing to the fact that it is strengthened 

 with a plastron of closely-arranged abdominal ribs (abd.). The bones 

 are very slender, much more delicate than the thoracic ribs, and are 

 seen again, although scattered and displaced forwards, in Mr. Taylor's 

 second specimen. 



All the characters of the skeleton which have not been enumerated 

 in the foregoing pages are more or less doubtful, and among these 

 are unfortunately some of fundamental importance for the deter- 

 mination of the affinities of the new animal. As originally pointed 

 out to me by Mr. William Taylor, when he showed me the fossils, the 

 extreme lightness of the whole skeleton and the peculiar mechanical 

 adaptation of the hind limbs suggest comparisons with a bird; but the 

 observable parts of the head, fore-limbs, and pubis prove that the 

 animal is a reptile. Among reptiles, it can only be compared with 

 the B.hynchosauria, Parasuchia, and Dinosauria; but lack of know- 

 ledge, especially of the pectoral arch below the scapula, prevents 

 determination by strict rule. The pelvis is very different from that of 

 the known Rhynchosaurians ; while the absence of bony armour and 

 the apparent perforation of the pelvic acetabulum distinguish the 

 animal from the ordinary Parasuchia. So far as preserved, how- 

 ever, most of the characters agree well with those of the Dinosauria, 

 especially the American Triassic genera described by Marsh. 1 

 Compared with the latter, the new Elgin fossil is remarkable for the 

 relatively-large size of the head, the apparently-toothless jaws, and 

 the firm union of four long metatarsal bones in the foot. "These 

 are the characters of a hitherto unknown genus, which may be 

 named ScleromGchlus ('hard fulcrum'); the type-species being 



1 Anchisaurus, Ammosaurus, and Hallopus, Marsh, ' The Dinosaurs of North 

 America ' 16th Ann. Rep. U.S. Geol. Surv. 1894-95, pt. i [1896] pp. 147-55 & 

 pis. ii-iv, vi. Hallopus is regarded as Lower Jurassic bv Marsh, but referred to 

 the Trias by Williston, Journ. Geol. Chicago, vol. xiii (1905) p. 338. 



