MUSEUM OF COMPARATIVE ZOOLOGY. 39 
DESCRIPTION OF THE PLATES. 
PLATE I. 
Entire figure, #4; natural size; side of head, about 3 nat.; ventral fins from 
beneath. 
PLATE I. 
Front view of head, with open mouth. 
PLATE III. 
Upper view of head. 
PLATE IV. 
Head as seen from beneath. 
PLATE V. 
The fourth gill-opening. 
PLATE VI. 
Teeth, six times nat. Figs. 1 and 5, upper view; Figs. 2 and 6, as seen from 
behind; Fig. 3, from the side; Fig. 4, from beneath; and Figs. 7 and 8, from 
the front. 
Scales. Fig. 9, from middle of the flank; Fig, 10, from the side of the tail on 
the lateral line ; Fig. 11, upper edge of tail; Fig. 12, at angle of mouth; Fig. 13, 
from middle of belly. Fig. 9 seven times, and Figs. 10-13 five times nat. 
PLATE VII. 
A. Skull, hyomandibular, and pterygo-quadrate from above, natural size. 
a, rostrum ; 4, fontanelle ; ¢, nostril; d, nasal sac; e, preorbital canal; 4 preor- 
bital process ; g, postorbital process ; 4, supraorbital pores; %, epiotic or postpari- 
etal pore; /, backward extension of articular facet for hyomandibular or pterotic 
process ; m, vertebre; x, parietal fossa and aqueducts of the vestibule ; 0, rugose 
space on frontal region; p, frontal slit; Am, hyomandibular; g-pg, quadrato- 
pterygoid; g-p, quadratic process of pterygo-quadrate; v, rostral sinus; ¢, epiotic 
process. 
B. Skull in longitudinal section (reversed in drawing). g, aqueducts of the 
vestibule ; so, supraoccipital crest ; fim, foramen magnum; zc, notochord; do, 
basioccipital ; zc, internal carotid; py, pituitary excavation; w and r+, bridges. 
Numbers 2-10, second to tenth pairs of nerves. 
VOL. XII.— No. 1. 3 
