Reviews — Dona's Dinosauria of Bernissart. 127 



ment of the lateral trochanter to the femur, may be taken as 

 evidence of aquatic habits for these Dinosaui-s, which are supposed 

 to have frequented marshes, and to have been, like Crocodiles, more 

 frequently in water than on land. And on this view the bipedal 

 position is regarded as a protective adaptive modification, by wliich 

 the animal was enabled to discover carnivorous enemies and 

 encounter them with advantage. 



At this point M. Dollo diverges into an interesting note on the 

 presence of the third trochanter in birds, and on its function. 

 Describing the femur of the Crocodile and bird, it is stated that the 

 femur of Iguanodon is constructed upon the avian plan, and this view 

 is supported by a dissection of the Wild Duck, in which, as in the 

 Bernicle Goose, and Swan, a faint indication of the lateral Dinosaurian 

 trochanter is found. The author shows that the distal portion of 

 this ridge in birds gives attachment to a small caudo-femoral muscle 

 (which, however, was large in some Dinosaurs, such as Ortliomerus 

 Dolloi), and to a large proximal ischio-femoral muscle. Accordingly, 

 the trochanter which occupies the middle of the inner side of the 

 shaft in a Dinosaur is attributed to these muscles. It is probable 

 that this explanation may be substantially correct ; only the tail of a 

 Dinosaur is so essentially the tail of a Crocodilian, that we must 

 suppose its muscular structure to have resembled that of the 

 Crocodile's tail, in which the transverse division of the caudal 

 muscular masses is as well marked as in other cold-blooded 

 Vertebrata. I would especially urge that, even if this homology of 

 the lateral trochanter is beyond question, it does not in itself quite 

 establish the view that the Iguanodon femur is built on the bird 

 type, or used under conditions like those of a bird's femur. 



In common with many other naturalists, M. Dollo prefers to 

 name the lateral trochanter the fourth trochanter, reserving the 

 name third trochanter for the process usually so named in mammals. 



The fourth note is devoted to the skull and axial skeleton. 

 Commencing with the mandible, it is shown that the coronoid 

 process occupies an unusually backward position, and that the teeth 

 extend behind it, as far as the middle of the temporal fosse. In 

 addition to the dentary, coronoid, and articular bones, which are 

 seen on both sides of the jaw, the angular, surangular, and splenial 

 bones are visible only on the inner side. Anteriorly, in front of 

 the dentary bone, forming a horse-shoe-shaped extremity to the jaw, is a 

 bone which the author names pre-symphysial, and which Mr. Hulke 

 has named pre-dentaiy. It is convex externally, concave internally, 

 and its upper border, relatively thin, rises into bony processes like 

 denticles. This ossification appears to characterize the group of 

 Dinosaurs allied to Iguanodon, and probably gave a cutting surface 

 to the front of the jaw, comparable to that seen in Chelonians. 

 The author would compare it to a representative of the two pieces 

 which unite the i-arai of the mandible of anourous Batrachians, which 

 Professor Albrecht terms inferior intermaxillaries ; and as these 

 elements carry teeth in Amphignathodon Guentheri, the author believes 

 that a like toothed condition is developed in MypsilopJiodon. Detailed 



