[Illustration: Fig. 28. Restoration of probable appearance of _Amphibamus grandiceps_ Cope on the basis of the material described herewith. × 1.5.] In the type specimen the matrix in the orbit was blackened as if by the _pigmentum nigrum_ of the choroid. The same has been noticed in other specimens. Professor Cope thought this indicated that the animal was nocturnal. There are many characters in _Amphibamus_ which seem to approximate the reptilian type of structure. Among these may be mentioned the character of the articular surfaces of the limb bones, the intercentral position of the ribs, the incipient double-headedness and the curvature of the ribs, the presence of a cartilaginous calcified pubis, the length of the limbs, and the clawed character of the phalanges. _Amphibamus_ was a low, flat, short, and undoubtedly a creeping, crawling animal, possibly spending a portion of its time in the water; but it could not have been a swimmer. It was one of nature's first attempts at constructing a land vertebrate. Measurements of Amphibamus grandiceps Cope. Collection of Mr. L. E. Daniels, of Rolling Prairie, Indiana: mm. Entire length of specimen 62 Posterior width of head 15 Length of head 15 Posterior height of skull 3 Length of orbit 5 Width of orbit 3.5 Interorbital width 4 Width of skull in front of orbits 11 Width of skull just back of orbits 16 Length of presacral region of the vertebral column 30 Length of tail 13 Length of fore limb 13.5 Length of humerus 4 Length of radius and ulna 3 Length of right hand as preserved 3.5 Length of rib along curve 5.5 Length of hind limb 17 Length of ilium 4 Length of vertebral centrum 1.75 Length of portion of scapula (?) preserved 4.5 Length of foot 6.5 Width of impression of body midway 16 No. 794 (1234), Yale University Museum: