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EXPLANATION OF THE PLATES. 



PLATE I. 



Fig. 1. — Vertical section of the skin of Amiurus from the lateral region of 

 the trunk. 



Zeiss D, Oc. II., cam. luc. 

 pc. pigmentary layer of corium. 

 p. palisade cells of epidermis. 

 s. spindle-shaped intermediate cells. 

 cl. clavate cells. 

 p.e. interepithelial pigment cells. 

 m. mucous cells. 

 Fig. 2. — Vertical section from skin of dorsal surface of head. Zeiss A, Oc. II., 

 cam. luc. fc. fibrous ; ac. adipose layer of corium ; pap. papillae ; 

 cl. points to a clavate cell projecting beyond the level of the 

 epidermis. 

 Fig. 3. — Vertical section of abnormally thickened skin as described in text. 



pap. points to one of the branched papillae. 

 Figs. 4, 5, 6. — Dorsal, ventral and lateral aspects of cephalic end of young 



Amiurus to show the openings of the mucous canals. 

 Fig. 7. — Vertical section of supraorbital mucous canal of young Amiurus 



(25 mm.) Zeiss H. I. ^th, Oc. II., v. Text. 

 Fig. 8. — Horizontal section through a macula acustica neglecta from a fish of 

 similar size under same enlargement, ot. otolith ; sc. spindle- 

 celled cartilage ; v. vessel. 

 Fig. 9. — Auditory labyrinth from medial aspect, a.s. a.h. ag. ampullae of the 

 sagittal, horizontal, and frontal semicircular canals ; lap. as. sag. 

 lapillus, asteriscus and sagitta in the recessus utriculi, lagena 

 cochleae, and sacculus respectively. 

 Fig. 10. — The same from lateral aspect — osmic preparation — showing the 

 branches of the Rr. anterior and posterior of the auditory 

 nerves. 



1. Ramus ampullae sagittalis. 



2. R. amp. horizontalis. 



3. R. recessus utriculi. 



4. R. neglectus. 



5. R. amp. frontalis. 



6. R. lagense. 



7. R. sacculi. 



Fig. 11. — Partes inferiores of both sides, with the amp. front, from above to 

 show the relation of the R. sacculi to the duct, endolymph (d.e.) 

 and sinus impar. (s). 



Fig. 12. — Right nasal sac, natural size, opened from above, ap. ant. and 

 post, anterior and post narial apertures. 



