420 



Reviews — Gauclnj's Animal World. 



the author adopts as genera the numerous terms which have heen 

 proposed of late years, and figures several specimens (figs. 190, 191) 

 exhibiting the rare feature of the complete mouth. The figures 

 of the various modifications of the sutures of the lobes given on 

 pp. 114, 115, will be found interesting and instructive. 



Passing by the sixth chapter, which is devoted to the Brachiopods 

 and Arthropods, we commence the Vertebrates with the seventh 

 chapter ; these occupying the remainder of the volume. In the 





Fig. 3. — Skeleton of Lates Heberti; from the Pisolite of Mt. Aime. f nat. size. 



chapter on Fishes the author traces the gradual tendency to a loss 

 of a bony scale-armour as we advance in geologic time, and likewise 

 the gradual increase in the degree of ossification of the endo-skeleton. 

 We have selected the figure of the skeleton of Lates (Fig. 3), and of 

 the jaw of Mesodun (Fig. 4) as good specimens of the illustrations 

 in this chapter. 



Fig. 4. — Outer side of the left ramus of the mandible of Mesodon profusidens ; 

 from the Neocomian. f . 



Under the heading Eeptiles the author includes both the animals 

 properly so called and also the Amphibians. In treating of the 

 Labyrinthodonts, the Professor expresses strong doubts whether the 



