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EXPLANATION OF THE PLATES. 
PLATE I. 
Fie. 1.—Vertical section of the skin of Amiurus from the lateral region of 
the trunk. 
Zeiss D, Oc. II., cam. luc. 
pe. 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. 
Fie. 2.—Vertical section from skin of dorsal surface of head. Zeiss A, Oc. II., 
cam. luc. fe. tibrous ; ac. adipose layer of corium ; pap. papille ; 
cel. points to a clavate cell projecting beyond the level of the 
epidermis. 
Fie. 3.—Vertical section of abnormally thickened skin as described in text. 
pap. points to one of the branched papille. 
Figs. 4, 5, 6.—Dorsal, ventral and lateral aspects of cephalic end of young 
Amiurus to show the openings of the mucous canals. 
Fic. 7.—Vertical section of supraorbital mucous canal of young Amiurus 
(25mm.) Zeiss H. I. sth, Oc. II., v. Text. 
Fie. 8.—Horizontal section through a macula acustica neglecta from a fish of 
similar size under same enlargement. of. otolith ; sc. spindle- 
celled cartilage ; v. vessel. 
Fic. 9.—Auditory labyrinth from medial aspect. a.s. a.h. ag. ampulle of the 
sagittal, horizontal, and frontal semicircular canals ; lap. as. sag. 
lapillus, asteriscus and sagitta in the recessus utriculi, lagena 
cochleae, and sacculus respectively. 
Fic. 10.—The same from lateral aspect—osmic preparation—showing the 
branches of the Rr. anterior and posterior of the auditory 
nerves. 
1. Ramus ampulle sagittalis. 
. amp. horizontalis. 
. recessus utriculi. 
. neglectus. 
. amp. frontalis. 
. lagene. 
. sacculi. 
Fie. 11.—Partes inferiores of both sides, with the amp. front. from sbove to 
show the relation of the R. sacculi to the duct. endolymph (d.e.) 
and sinus impar. (s). 
Fie. 12.—Right nasal sac, natural size, opened from above. ap. ant. and 
post. anterior and post narial apertures. 
AST w& 
Dm mma 
