THE SENSORY CANAL SYSTEM OF FISHES, 535 
80. Traquarr, R. H.—‘On the Cranial Osteology of Polypterus,” 
‘Journ. Anat. and Phys.,’ 1870, vol. v, pp. 166—183, pl. vi. 
81. Trrevrranus, G. R.—‘‘ Ueber die Nerven des fiinften Paars als Sinnes- 
nerven,” * Vermischte Schriften anat. und phys.,’ 1820. 
82. Wine, J. W. van.—“ Ueber das Visceralskelett und die Nerven des 
Kopfes der Ganoiden und von Ceratodus,” ‘ Neiderland. Arch. f. 
Zool.,’ 1882, Bd. v, pp. 207—320, Taf. xv, xvi. 
88. Wise, J. W. van.— Ueber die Mesodermsegmente und die Entwicke- 
lungsgeschichte der Nerven des Selachierkopfes,” ‘ Natuurk. Verhandh. 
Akad. Amst.,’ 1882, xxii. 
84, Wricut, R. Ramsey.—“‘On the Skin and Cutaneous Sense-organs of 
Amiurus,” ‘Proc, Canadian Inst.,’ 1884, vol. ii, pp. 251—269, part 
of pl. i. 
DESCRIPTION OF PLATES 39 and 40, 
Illustrating Mr. Walter Edward Collinge’s paper, “ The 
Sensory Canal System of Fishes.” 
Fig. 1.—Dorsal view of the skull of Polyodon folium, showing the 
cranial elements and canal bones. The stellate-shaped bones on the rostrum 
are shown on the left-hand side, and the epidermis also in the most anterior 
portion. Lettering as below. 
Fic. 2.—Lateral view of Polyodon, showing the course and branching of 
the lateral canal, its position on the caudal fin, and the groups of primitive 
pores on the head, &c. Lettering as below. x 4. 
5 
Fie. 3.— Diagrammatic view of the side of the head of Polyodon, showing 
the course of the main canal of the head and its branches. 
Lettering.—com. Commissure in occipital region. c. p. Cluster pores. 
d. ec. eth. Dermo-ect-ethmoid. d. eth. Dermo-ethmoid. d.sph. Dermo-sphenotic. 
Jr. Frontal. yom. 6. Hyomandibular branch of the main sensory canal. 
Z.c. Lateral canal. 7. ¢. 4. Branches of the lateral canal. m. Mouth. WM. C. 
Main canal of the head. Mz. 6. Mandibular branch of the main canal. Mz.d. 
Maxillary branch of the main canal. zar. Nares. op. Operculum. or. Orbit. 
pa. Parietal. pp. Primitive pores. p¢. Post-temporal. sp. Spiracle. 8. or. 
Suborbital branch of the main canal. Sp. 0. Supra-orbital branch of the 
main canal. «. Branches in the pre-orbital region. 
Fic. 4.—Longitudinal section through a cluster pore from the occipital 
region of the head of Polyodon. Lettering as below. 
