OF THE VOMEE, ETHMOID, AND INTEEMAXILLAET BONES, 
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rine lamina ; d, nasals ; e, central plate of the ethmoid ; f, lateral ridge of the 
vomer peculiar to marsupiate animals. 
Fig, 24. Part of the skull of the Dugong: — a, frontal; b, intermaxillary; c, vomer; 
d, maxillary ; e, e, palatals ; ethmovomerine laminae and lateral masses of 
the ethmoid. 
Fig. 25. Section of skull of Belphinus orca : — a, intermaxillary ; b, maxillary ; c, c, vomer ; 
d, palatal ; e, central plate of the ethmoid. 
Fig. 26. Skull of DelpMnus globiceps from above: — a, intermaxillary ; 5, maxillary ; 
c, palatal ; d, pterygoid ; e, nasal foramen of palate-bone ; central plate of 
the ethmoid ; g, expansion of the ala of the vomer ; Ji, the part of the frontal 
which would have been concealed by the nasal, had not that bone been 
removed. 
Fig. 27, Diagram of the two most anterior segments of the mammalian skull, and of the 
neural arches of the other segments. The dotted part represents the extent 
of the septal cartilage. The centra are darkened. Two dotted lines and 
arrowheads show the direction of the anterior haemal arches: — a, occipital 
segment ; b, auditory segment ; c, sphenoparietal segment ; d, optic segment ; 
frontal bone ; /*, central plate of the ethmoid ; g, lateral mass of the ethmoid ; 
h, vomer ; % palatal ; nasal ; m, intermaxillary ; n, maxillary. 
Fig. 28. Vomer and palatals of the Duck, viewed from above. 
Fig. 29. A. Section of the skull of the Cod. The cranial cavity is represented dark ; 
the cut surfaces of bones are marked with oblique lines, and the cartilages 
are left white, while the interorbital septum is dotted: — a, intermaxillary; 
b, vomer ; c, basisphenoid ; d, basioccipital ; e, nasal ; f, frontal ; g, supra- 
occipital. 
B. A similar section through the nasal and vomer, after the cartilage has been 
removed : — b, vomer ; e, nasal ; h, prefrontal. 
Fig. 30. A. Intermaxillary and vomer of Python : — «, intermaxillary ; b, vomer, 
B. Nasal and vomer of Malaj)terurus \ — nasal; b, vomer. 
Fig. 31. Diagram of the two most anterior segments of the skull of the fish : — a, pre- 
frontal ; b, vomer ; c, palatal ; d, nasal ; e, intermaxillary ; f, maxillary ; g, a 
dotted circle indicating the position of the nostril. The centra are darkened. 
The dotted lines and arrowheads show the direction of the haemal arches. 
2 X 
MDCCCLXII. 
