678 PLAGIOSTOMATA OP THE PACIFIC 



EXPLANATION OF PLATES XLV. and XLVI. 



Lettering followed tJiroughout all the figures on both Platen : — 

 a. — Superior oral fold. 

 a'. — Continuation of the superior oral fold, enclosing the lower oral 



fold and forming a second inferior oral fold. 

 h. — Inferior oral fold, 

 y.— Internal nasal flap. 

 n. — External orifice of the nasal groove. 

 Sp. — Jjpiracle. 



Plate XLV. 

 Hetcrodontus zebra. Grey. 



Fig. 1. — Young 9 from above. (From a photo.) A little more than twice 



the natural size. 

 Fig. 2. — The same from the side. 



Fig. 3. — Ventral aspect of the anterior part of the head of the same. 

 Fig. 4. — One of the anterior 5-cusped teeth. (About four times the 



natural size.) 

 Fig. 5. — One of the lateral cuspidated teeth. (About four times the 



natural size. ) 

 Fig. 6. — Lateral view of the anterior part of the head. (About twice the 



natural size.) 

 Fig. 7. — The same view, but with the internal nasal flap ffj lifted up. 

 Fig. 8.— Outline of the upper portion of the head from the front, to show 



the supra-orbital ridges. 



Plate XLVI. 



Fig. 1-6. — Miliobatin punctatus. Mel. 



Fig. 1. — The same from above. 



Fig. 2. — Ventral aspect of the same. 



Fig. 3. — Lateral view of the head. 



Fig. 4. — Ventral view of the head, to show the general shape of the snout 



and of the mouth, and the papillae on the palate and the sides of 



the mouth, half natural size. 

 Fip:. 5. — The larger of the' two barbed spines. (Natural size.) 

 Fig. 5'. — A portion of the same twice enlarged, to snow the shape of the 



lateral l>arbs. 

 Fig. 6. — The smaller of the two barbed spines. (Natural size.) 

 Fig. 7-15. — Discobatis marginipinnis. Mel. 

 Pig. 7. — The same from above. 

 Fig. 8. — Ventral view of the same. 

 Fig. 9 — The eye and spiracle from the side. 

 Fig. 10.— Mouth and nostrils. The skin below tlie mouth appears tuber- 



culated. 

 Fig. 11. — The same as Fig. 10, 1)ut the nasal iiap on one side is uplifted, to 



show the mouth and its communication with the nasal cavity. 

 Fig. 12. — View of the mouth from the inside, to show the notched pal5.tal 



fold. 

 Fig. 13. — Teeth of the upper and lower jaw. Slightly enlarged. 

 Fig. 14. —Front teeth, enlarged about four times. 

 Fig. 15. — Teeth of the lower jaw with longer and more pointed cusps. 



