574 APPENDIX 



Note thyroid gland lying between two great strands of 

 muscle. Remove thyroid and muscle strands ; note ventral 

 aorta ; trace afferent branchial arteries (Fig. 257). 



b. Cut through the jaw and branchial arches on one side, turn the 

 floor of the mouth outwards, and remove mucous membrane 

 of roof of mouth. Note gill-clefts. Find: gills and pseudo- 

 branch ; efferent branchial and epibranchial arteries ; dorsal 

 aorta ; common carotid, internal carotid, and point of origin 

 of external carotid arteries ; subclavian and cceliac arteries 

 (the latter found by tracing back dorsal aorta) (Fig. 258). 

 8a. Cut through the skin round the eye and pull the eyeball 

 outwards. Note, in orbit : eyeball, internal, superior, and 

 external recti muscles ; superior oblique ; optic nerve, fourth 

 nerve (Fig. 265). 



b. Remove the eye by cutting through the six muscles and the optic 

 nerve, close to the eyeball. Note : four recti muscles, two 

 obliques, second, third, and fourth nerves, maxillary, 

 mandibular, and ophthalmic branches of fifth nerve, hyo- 

 mandibular, prespiracular, palatine, and ophthalmic branches 

 of seventh (Fig. 266). 



t. Cut away roof of cranium and neural arches. Note : olfactory 

 lobes, cerebrum, thalamencephalon, optic lobes, cerebellum, 

 medulla oblongata, restiform tracts, fourth ventricle, spinal 

 cord, roots of all cranial nerves except sixth, spinal nerves 

 (Fig. 262). 



d. Slice horizontally through the auditory capsule until nerves 



passing through it are exposed ; then slit open the anterior 

 cardinal sinus and trace distribution of these nerves. Note : 

 semicircular canals ; roots of ninth and tenth cranial nerves ; 

 ninth passing to first branchial arch, with branch to hyoid arch ; 

 branches of tenth to branchial arches 2-5, each with secondary 

 branch to preceding arch, other branches of same nerve to 

 lateral line, and to heart and viscera (Plate XVIII.). 



e. Cut through nerves and remove the brain. In ventral view, 



note : olfactory lobes, cerebrum, optic chiasma and nerves, 

 infundibulum, lobi inferiores and sacci vasculosi, crura cerebri, 

 medulla oblongata, restiform tracts ; roots of third and of 

 fifth to tenth cranial nerves (Fig. 263). 

 9. Draw the skeleton in the following sections : cranium (side, 

 dorsal, and ventral views) ; jaws and branchial arches ; 

 vertebral column (side view of portions of trunk and tail 

 regions, longitudinal section) ; pectoral girdle and fin ; pelvic 

 girdle and fin (Figs. 248-250 and Plate XIX.). 

 In order to obtain these fish in inland places with the viscera 

 The Ood i (or intact a special order must be given to a fishmonger. 

 Haddock or I . It will usually not be possible to observe the 



whiting). animal alive, but a study of the habits of a bony 



1 The student! who has not already studied the dogfish or some other fish is 

 recommended to read the paragraph at the bottom of p. 341, and also to note the 

 following facts : — 



In the cod, haddock, and whiting, the body is coated with scales which are thin, 



