1876.] PROF. T. H. HUXLEY ON CERATODUS FORSTERI. 



51 



pterygium of Gegenbaur, I) is relatively small ; but the enlarged post- 

 axial cartilage {metapterygmm, Mt) has extended upwards along the 



Fig. 11. 



ICHTHYOSAURUS 



The left pectoral fin of Cestracionphilippi (letters as before), tbe left fore limbs 

 of IcMhyosmmis, Plesiosaurus, Menobranchws, and the left manus of Gecko 

 verus. 



I, humerus; ff, radius; f7, ulna; r, radiale; i, intermedium ; m, ulnare; c, cen- 

 trale; c', c^, c^, c*, c^ distal carpals; 1, 2, 3, phalanges of Menobranchus. 

 In Gecko it is uncertain whether x represents the intermedium and the ulnare 

 coalesced as in Menobranchus {i u), or whether x is the intermedium and 

 p is the ulnare, occupying the place of a pisiform bone. 



postaxial face of the first, until it has not only reached the articular 

 surface of the pectoral arch, but furnishes a large part of the articular 



4* 



