156 PKOFESSOR STRUTHERS. 



and wide palato- maxillary fissure to be noticed with the nasal 

 cavity. 1 



6. MALAR BONE. In Megaptera the malar bone is much 

 broader (2| inches) along its posterior half than in B. musculus ; 

 much more deeply grooved at each end, transversely, to receive 

 the zygoma and maxillary ; and its enlargement at the maxil- 

 lary end (5 inches in breadth, 2J in length) is abrupt and at 

 right angles to the rest of the bone. In B. musculus the 

 enlargement (4 to 5 inches in length, 3J in breadth) is more 

 gradual, and is in the direction of the curve of the bone, pushing 

 in below the lachrymal. At the posterior end, in B. musculus, 

 there is an abrupt process, half an inch long, like the end of the 

 little finger, projecting inwards. The outer edge of the malar 

 in B. musculus appears unfinished, as if it had been covered with 

 cartilage. 



7. THE ORBIT. The opening of the orbit is larger in Megap- 

 tera, about the same in length, but greater in height (8 inches, 

 in B. musculus 7). This is owing to the much greater curve of 

 the upper edge of the frontal plate in Megaptera (concavity 3 

 inches deep, and uniform); in B. musculus there is very little 

 curve on the anterior three-fourths of the frontal edge, the 

 bend down being on the posterior fourth. In front of the orbit, 

 the frontal plate presents the same difference for about a third 

 of its breadth, convex in Megaptera, flat in B. musculus. In 

 the roof of the orbit the same difference in the concavity is 



1 The parts which assist to close the orbital cone below are more conveniently 

 studied with these parts than with the orbit viewed externally. In B. musculus 

 the two curved laminae alone form the cone all the way in, the posterior scroll, 

 as in all the finners, below the anterior, where they meet and cross for a little. In 

 Megaptera the cone is covered and as if supported below by the following parts, 

 from within outwards. (1) The suborbital process of the temporal bone, above 

 noted as crossing the pterygoid, supports the pterygoid at the base of the pedicle. 



(2) The angular process of the palate bone supports the pterygoid from before. 



(3) The pterygoid bone sends a process outwards below the cone for 3 inches ; it 

 rises higher and reaches farther out before than behind, rising to the height of 

 the anterior scroll that is, an ascent of 1| inch on the pedicle. (4) The parietal 

 bone, external to the pterygoid, covers the cone below for 3 inches. This is to 

 within 5 inches of where the two scrolls diverge and open the cone outwardly. 

 Over these 3 inches the parietal turns well up in front, to as high as the edge of 

 the anterior scroll. The great extension of the parietal on the back of the cone, 

 the post-orbital bar, has been noted above. The two last-mentioned additions 

 give the orbital cone a blunt keel-shape and smooth surface below, in contrast 

 with its flatness and roughness in B. musculus. 



