FAUNA OF THE GOSAU FORMATION. 



667 



measurement remains unaltered, but the side-to-side measurement 

 is reduced to ^--J inch ; where the specimen is fractured proximally, 

 the antero-posterior measurement is -^-J inch, while the measurement 

 from side to side in the middle of the shaft is inch. The right 

 tibia (fig. 19) does not appear to be crushed ; but the left specimen 

 is somewhat fractured at its distal end. The inner side in both is 

 flattened, though not quite so flat as in the larger species. The outer 

 side is convex, but divided into two portions by a median ridge, 

 which in its upper 3j inches is strongly muscular, though the 

 markings appear to be stronger on the left tibia than on the right — 

 a condition the reverse of that which obtains in the larger species. 

 The muscular ridge is made up of three or four close parallel ridges. 

 The posterior half of this side of the bone appears to be more flattened 

 than in the larger species, while the anterior half shows indications 

 of a similar longitudinal concavity, though the specimens are frac- 

 tured too low down for more than the beginning of it to be detected. 

 The proximal fracture displays a triangular outline with a long 

 straight base formed by the inner side and two shorter converging 

 sides which form the outer side. Here the bone is less than twice 

 as deep as it is wide. On the posterior side, as compared with the 

 larger species, the side-to-side compression is greater towards both 

 the proximal and distal ends, while anteriorly the bone is rather 

 more rounded from side to side. There is about as much difference in 

 size between the two types of tibiae as there is between the two kinds 

 of femora, though, so far as can be judged from the fragments 

 preserved, the differences in essential characters in the tibiae were 

 less important than those of the femora. 



There have also been found fragments of patelloid ridges of 

 tibiae which appear to belong to a species slightly larger than either 

 of these ; but the materials are too imperfect for description, or even 

 for absolutely certain osteological identification. 



Fibula. 



The specimen which Biinzel (pi. iii. f. 12, 13) regarded as the 

 upper half of the left humerus of a Crocodile is undoubtedly a 

 somewhat obscure fossil. It, however, presents nothing in common 

 with any crocodilian humerus with which I am acquainted, espe- 

 cially differing in its remarkable compression, in wanting all trace 

 of a radial crest, in the lateral compression of the shaft at right 

 angles to the supposed head of the bone, and in the inflation of 

 the inferior side of the head. While, therefore, I have no hesitation 

 in affirming that the specimen is not crocodilian and not a humerus, 

 the loss of the terminal articular end and the evidence of a certain 

 amount of crushing makes any other determination a matter re- 

 quiring some caution. The contour, however, of the bone is so 

 similar to that of the tibia of Cratceomus, and one aspect, and especi- 

 ally the posterior margin, is so roughened with muscular attach- 

 ments, that I have little hesitation in affirming that we have here 

 the fibula of one of the Dinosaurs — a view which is further sup- 



