784 THE AMERICAN NATURALIST.  [Vor. XXXIV. 
Musculature of Leg. — Dollo (83, 2) adds an extremely 
interesting resemblance in his comparison of the attachment of 
the muscles connecting the back of the femur with the ischium 
and with the caudal vertebre in birds and in Iguanodon; he 
shows that the so-called “third trochanter” of birds and 
dinosaurs, to which the name “ fourth trochanter” should be 
Fic. 3.— Right hind limb of duck (Anas boschas), showing, £74, the supposed 4th trochanter; 
i.f., ischio-femoral ; c.f., caudo-femoral muscles. After Dollo. 
applied, is actually a process quite distinct from the * third 
trochanter” of mammals, that its function is especially for the 
insertion of the “ischio-femoral” muscle and for the origin of 
the ** caudo-femoral " muscle; he concludes that the femur of 
Iguanodon is constructed upon the bird and not upon the 
reptilian type, and, as a corollary of this, that the extrinsic 
musculature of the tail in Iguanodon presented close resem- 
blances to the corresponding musculature in the bird. As 
