MUSEUM OF COMPARATIVE ZOOLOGY. 33 



DESCRIPTION OF THE PLATES. 



PLATE I. 



Entire figure, ^\ natural size ; side of liead, about | nat. ; ventral fins from 

 beneath. 



PLATE II. 



Front view of head, with open moutli. 



Upper view of head. 

 Head as seen from beneath. 

 The fourth gill-opening. 



PLATE III. 

 PLATE IV. 



PLATE V. 

 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 month ; 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 ; b., fontanelle ; r, nostril ; d, nasal sac ; <?, preorbital canal ; f, preor- 

 bital process; g, postorbital process ; h, supraorbital pores; k, epiotic or postpari- 

 etal pore ; /, backward extension of articular facet for liyomandibular or pterotic 

 process ; m, vertebrae ; n, parietal fossa and aqueducts of the vestibule ; o, rugose 

 space on frontal region; p, frontal slit; hm, hyomandibular; q-pff, quadrato- 

 pterygoid; q-p, quadratic process of pterygo-quadrate ; r, rostral sinus; t, epiotic 

 process. 



B. Skull in longitudinal section (reversed in drawing). </, aqueducts of the 

 vestibule ; so, supraoccipital crest ; fm, foramen magnum ; nc, notochord ; bo, 

 basioccipital ; ic, internal carotid ; pj/, pituitary excavation ; to and r, bridges. 

 Numbers 2-10, second to tenth pairs of nerves. 



VOL. XII. — NO. 1. 3 



