1883.] Geology and Palaeontology. S69 
THE “ THIRD TROCHANTER ” OF THE Dinosaurs.—M. L. Dollo 
has recently instituted a comparison between the trochanters upon 
the femur of Iguanodon and those of Anas, Bernicla and Cyg- 
nus, and announces his conclusion that the so-called “ third tro- 
hanes ” of the former (and of other Dinosaurs) is found also in 
the avian genera mentioned. The great resemblance between 
the dinosaurian and avian femur was noted by Huxley in 1870, 
and has been generally admitted, but the absence, in most birds, 
of the third trochanter, which is so conspicuous a crest in Igua- 
nodon, has been a difficulty. 
M. Dollo figures, side by side, the femur of Cygnus atratus and 
that of Iguanodon BNA PR and the proof is evident that 
the bird possesses the same trochanter—the position is the same, 
the form very similar, but the size relatively far inferior 
Dissection proved that the duck’s third Koden serves for 
the insertion of the caudo-femoral muscle, which, as shown by 
Meckel, is the agent in the curious lateral movements made by 
the tail of the duck; and aiso for the insertion of the ischio- 
femoral muscle. 
The difference in the relative dimensions of the trochanters is, 
therefore, correlated with the difference in size of the tails of the 
two animals. The enormous tail of the Iguanodon needed for 
its movement a massive muscle, instead of ‘the thin slip present 
in the duck and swan. 
Hesperornis, a bird so reptilian in many respects, ought, there- 
fore, to have this trochanter, and M. Dollo remarks that although 
Professor Marsh did not note its significance, it is plainly shown 
in Plate xur of that author's work on the Odontornithes. 
This trochanter cannot be homologized with either of the 
three troshantees ound in mammals, since it serves for the inser- 
tion of a totally different set of muscles from those attached to 
either of them, and M. Dollo therefore proposes to distinguish it 
as the “ fourth trochanter.” 
Tue Puerco Fauna IN France.—Dr. Lemoine has published 
the second part of his Researches on the ch Birds of the In- 
ferior Tertiary of the neighborhood of Reims. In an introduc- 
tion he distinguishes the two faunz of the me of France, which 
peepee the beginning of the Tertiary, the Cernaysienne and 
he Suessonienne. These correspond with remarkable equality 
13 the Puerco and the Wasatch faunz, which I discovered on this 
continent. Not a few of the genera are common to the two con- 
abr but the extent of the identity cannot be fully understood 
the present state of our knowledge of the respective forms. 
Those of the Cernaysian fauna, as given by Lemoine, are the fol- 
ing: Mammalia: He teroboru us, Hyodectes, Hyznodictis, 
Lopbiodocharas by Pleuraspidotherium, Plesiadapis, Adapisorex, 
Ptilodus ; POE Champsosaurus, crocodiles, turtles and Lacer- 
