0/ 



The characters of the upper end of the tibia of the Dinomis 

 elephantopus closely accord with tliose of the Dinomis robustus, 

 and the difference of size, as exeniplified in the foregoing table, is so 

 slight, that had this extreinity only of the boue reached nie, I should 

 most probably have lefeired it to the Dinomis robustus. The 

 almost flat articular surface for the iuner condyle of the femur is 

 somewhat less in its shorter diameter ; the epicuemiai ridge is less 

 extended transversely ; the ectocnemial ridge curves more strongly 

 outvvards ; but there are individual varieties in all these characters in 

 the tibiae before me. All the tibise, hovvever, ditfer iu the earlier sub- 

 sidence of the ridge continued dowuwards from the procnemial plate, 

 which ridge is continued in Dinomis robustus uninterrupted by that 

 above the inner division of the distal trochlea. The space between 

 the ecto- and pro-cnemial platės in the Dinomis crassus is relatively 

 greater than in either of the above larger species ; the ridge con- 

 tinued from the procnemial plate is interrupted as in the Dinomis 

 elephantopus. The fore part of the tibia internal to the procnemial 

 ridge is impressed by irregular vascular grooves. The fibular ridge 

 is interrupted by a smooth tract, in or near which is the orifice of 

 the canal for the obliquely descending medullary artery in all the 

 species of Dinomis. The upper division of the ridge is shorter in 

 the Dinomis elephantopus than in the Dinomis robustus, and rela- 

 tively shorter than in the Dinomis crassus. The surface between 

 the fibular ridge and the inner border of the shaft at the back part 

 is concave transversely in Dinor?iis elephantopus, not merely flat as 

 in Dinomis robustus and Dinomis crassus, and, as it descends, it 

 continues louger a flat surface before it changes gradually to a couvex 

 one. The oljlong rough insertional surface above the inner condyle 

 is relatively shorter and better defined in the Dinomis elephantopus 

 than in the Dinomis robustus. On the characteristic fore part of 

 the lower end of the tibia, that bone in the Dinomis elephantopus 

 repeats all the modifications ascribed to the Dinomis in my memoir 

 on the Gastornis, or large fossil bird from the Paris eocene*. 



The teudiual canal inclines obliquely iuvvards parallel with the 

 inner border of the expanding end, near which it is placed ; the bouy 

 bridge spans across it from a flattened tubercle developed from the 

 lower part of the outer pier. The outlet of the canal is as wide as 

 in the Dinomis robustus ; its aspect is obliquely forvvards and down- 

 wards. Exterual to the tubercle is an obliąue rough depression, 

 relatively narrower and better defined than iu the Dinomis robustus. 

 The iuner condyle is relatively narrovverand more produced forwards 

 than iu the Dinomis robustus, resembling more the proportions of 

 that part in the Dinomis crassus. The general form and obliąue 

 direction of the wide distal trochlear articulation are closely repeated 

 in all the species, the canal being rather more sharply defined behind 

 in the Dinomis elephantopus than in the Dinomis robustus. The 

 depression on the entocondyloid surface is less deep in the Dinomis 

 elephantopus than in the Dinomis robustus. 



The above-specified differences, as well as all that I have noticed in 

 * ' Proceediiigs of the Geological bociety.' 



