EXPLANATION OF THE PLATES.

(See Plates XVI, XVII, XVIII, XIX, XX, XXI, XXII. )

Six of the following Plates are taken from drawings made by Mr. HOWSHIP, who very kindly undertook that task, during the indisposition of Mr. CLIFT, and his knowledge of anatomy, which he has cultivated with much ardour, induced me to solicit his assistance upon this occasion.

PLATE XVI.

Fig. 1. A view of the pectoral fin of the Squalus Maximus, from which the skin and cellular membrane are reinoved, to shew the arrangement of the cartilages of which it is composed.

Fig. 2. A portion of the elastic fibrous structure with which the fin is tipped, of its natural size.

PLATE XVII.

Fig. 1. An internal view of the stomach and duodenum of the Squalus Maximus.

a. The oesophagus.

bb. The cardiac portion of the stomach.

cc. The pyloric portion.

dd. The spleen.

e. A small cavity belonging to the stomach.

ff. The duodenum.

g. The band containing the hepatic ducts, six in number.

h. The dilatation in which the gall ducts terminate.

i. The opening of the pancreatic duct.

k. The spiral turns of the intestine.

Fig. 2. The fringe at the termination of the oesophagus of the natural size.

PLATE XVIII.

The heart of the Squalus Maximus laid open.

a a. A portion of the internal surface of the auricle.

bb. One of the vena cava laid open.

c. The valve between the auricle and ventricle.

dd. The cavity of the ventricle.

eee. The three rows of valves and the three intermediate spaces, along which regurgitation takes place when the canal of the artery is dilated.

ff. The strong muscular covering of the artery.

PLATE XIX.

A side view of the cerebellum, tubercula quadrigemina, and nerves of the brain of the Squalus Maximus.

3, 4, 5, 6, 7, 8. The different nerves going off from the brain corresponding with those in the brain of man.

a. Cerebellum.

bb. Two of the tubercula quadrigemina.

c. A third tuberculum mutilated.

PLATE XX.

A view of the upper surface of the cerebellum and nerves of the Squalus Maximus.

The nerves going off marked, as in the last Plate, beyond which are two pair of nerves belonging to the spinal marrow.