(502 BRITISH FOSSIL REPTILES. 



the claimed originality of his views of problematical pelvic bones by no means called for 

 any reflection on postal arrangements between Great Britain and the United States. The 

 impossibility might merely mean an oversight which left the writer ignorant of both 

 Cope's and Leidy's anticipations, as appears to have been the case with regard to von 

 Meyer's paper in the ' Isis' of 1830. 



In the "Further Evidence of the Affinity between the Dinosaurian Reptiles and 

 Birds," with confirmatory testimony by Professor Phillips, of Oxford,* Professor Huxley 

 adopts the ischial homology of the bone in question, and illustrates it by a diagram, 

 "Fig. 3, Dinosaur," p. 27 (tom. cit.), in which the supposed "ischium" is directed from 

 the acetabulum downward and backward, parallel with the pubis, with which it articu- 

 lates by the process (c, figs. 4 and 5, in Plate XX, " Omosaurus "), so as to " interrupt the 

 obturator space," and define, as in Birds, an anterior part of that space as an " obturator 

 foramen" (loc. cit.). 



To an advocate of the affinity of Dinosam-s to Birds and of the derivation of Birds 

 from Dinosaurs, such determination of the bone in question gave great help, and the 

 consequent diagram has been mainly subservient in gaining suffrages to the idea — I may 

 term it sensational — of the kinship of the Iguanodon with the Cassowary, carried to the 

 inference of a common bipedal mode of progression. 



The value of the genus Omosaurus, as of every well-determined nevi^ Dinosaur, to the 

 Palaeontologist desirous, irrespective of foregone conclusions, to lay the basis of lasting 

 views of affinity on fixed homologies, is here great. The bone, PI. 72, 63, which com- 

 pletes the acetabulum, shows by the extent and position of its articulation with the ilium, 

 from which it has been but slightly dislocated, that it is the ischium. The recovery of 

 the parial bone to the extent shown in PL 73, fig. 1, shows that the shaft gives oflf no 

 process ; also that an extension of the iliac articular end beyond the acetabular surface of 

 the ischium, and behind it, is the sole production, transverse to the axis of the bone, which 

 can be homologised with a non-articular process in the ischia of other Vertebrates. 



The ischia of Omosaurus being thus determined, the homology of the other pair of 

 pelvic bones (PI. 73, figs. 4 and 5), wrought out of the mass of matrix overlying the 

 haemal surface of the sacrum and ilia, was plain. They confirm the opinion of Professor 

 Leidy as to the nature of the bone ; and, so far as their dislocated condition indicated 

 their natural direction, it supports the conclusion of Professor Cope that they had " a 

 position similar to those in the Crocodilia," i. e., directed forward and downward, as 

 shown by Cuvier. in the ' Ossemens Fossiles,' tome v (1824), PL IV, fig. 15, a, PL V, 

 fig. G, and as exemplified in the diagram, Cut fig. 13, p b. 



So much of the homological ground being thus cleared, we may pass to the question 

 of the kinship or affinities it brings into view. 



In birds, as a rule, the pubis is a long simple style without process (fig. 15, ' Bird ') ; the 



* ' Quarterly Journal,' &c., torn, cit., p. 12. 



