38 



2. The bones of the leg, unequal in size and fused together at their distal 



ends. 



(a) The tibia, a stout straight bone, articulating at its upper end with the 



femur by two facets, at its lower end with the astragalus. 

 (6) The fibula, a slender bone, articulating at its upper free end with the 

 outer surface of the head of the tibia, at its fixed lower end with the 

 calcaneum. 



3. The ankle, composed of two rows of tarsal bones. 



(«) The proximal row, consisting of (1) the astragalus, on the inner side, 

 articulating with the tibia; (2) the calcaneum (os calcis), on the outer 

 side of the astragalus, articulating with the fibula and having its 

 hinder end produced into a large calcaneal process or heel. 



(b) The distal row, consisting of (1) the meso-cuneiform, a very small bone 



articulating with the navicular, (see c), and supporting the second 

 metatarsal bone; (2) the ecto- cuneiform, on the outer side of the meso- 

 cuneiform, articulating with the navicular and supporting the third 

 metatarsal bone ; (3) the cuboid, on the outer side, articulating with 

 the calcaneum and navicular, and supporting the fourth and fifth 

 metatarsal bones. 



(c) The central bone (navicular) immediately in front of the astragalus, 



articulating with the second metatarsal, and sending a large process 

 forwards along the ventral surface of the foot. 



4. The foot with four digits, each composed of a long metatarsal bone, and 



three phalanges, the last phalanx being modified to support a claw. 

 Note, on the outer side of the proximal end of the second metatarsal 

 bone, a backwardly directed process, probably representing the 

 metatarsal bone of the first (or lost) digit. 



K. General Dissection of the Brain. 



Remove the muscles of the neck from their attachment to the occipital part 

 of the skull : remove the skin from the whole of the cranial portion : and with 

 bone forceps and a stout blunt scalpel remove in pieces the bones of the skull 

 and expose the surface of the brain, working from the foramen magnum forwards 

 and taking special care not to injure the brain in the region of the ear bones. 

 Cut through the spinal cord behind the medulla ; and by help of the handle of a 

 scalpel, moistened with water, lift up the brain, cutting through the various 

 cranial nerves as far from the brain as possible. 



1. Observe the dura mater covering the brain and dipping down between 



the cerebral hemispheres, forming the falx cerebri ; and between the 

 cerebrum and cerebellum, forming the tentorium. Remove the dura 

 mater, and note the thin vascular pia mater closely enveloping the 

 brain. 



2. On the dorsal aspect of the brain note — 



(a) The large smooth cerebral hemispheres. 



