EXPLANATION OF PLATES. 



Plate. I. Vertebrate Animals. Fishes. 



Fig. 1. Plan of the circulation of tlie blood, after Yon Baer, Vorlesun- 

 gen ilher Anthropologie, Tab. iv, fig. 4. The heart is repre- 

 sented as divided into two poi'tions at a distance from each 

 other; I. II. the venous heart — i. the right auricle; ii. the right 

 ventricle; iii. iv. the arterial heart — iii. the left auricle; iv. 

 the left ventricle. The course of the blood is indicated by 

 the arrows. The upper half of the figure shews the motion 

 of the blood through the respiratory organs; the lower half 

 the course through the body, in which the arterial blood be- 

 comes venous. Compare p. 3. 



Fig. 2. Brain of Lophms piscatorius, natural size, seen from above. 

 I. Anterior cerebral lobes or hemispheres of the cerebrum, ii. 

 Middle cerebral mass, corpora quadrigemina. iii. Posterior 

 mass, cerebellum. A, Hypophysis, attached by a long pedicle. 

 1 First pair of cerebral nerves, &c. Compare pp. 43, 44. This 

 as well as the following figures of this Plate are from nature. 



Fig. 3. Perpendicular section of the basis of the skull of a new-born 

 child, to shew the bodies of the tliree cranial vertebrse. In 

 front of III. is the vomer or body of the fourth ; see p. 8, nat. 

 size. 



Fig. 4, Skull of the pike, Esox lucius, half the natural size and seen 

 from the side, to illustrate the osteology of fishes : compare 

 pp. 18 — 23. For more convenient comparison, the bones are 

 marked with the same cyphers as those used by Cuvier in the 

 skeleton of the j)erch in his Hist. nat. des Poisso7is, but the small 

 size of the figure does not allow all the cyphers to be given. 

 Those noted are 1 the frontal bone, the frontale posterius of 



