ME. "W. H. FLOWER ON THE OSTEOLOGY OF THE SPERM-WHALE. 319 



the great convex surface formed by the occipital crest. The chief peculiarity of this 

 region is the apparent suppression of the parietal bone, the squamosal and the frontal 

 uniting in a vertical suture for more than the lower half of the fossa, and being 

 separated by a wedge-shaped piece (^j) of the supraoccipital above. A faint superficial 

 groove, more strongly marked, but still only a groove, both in the young skull and in 

 the foetal skull but 34" long, indicates that this wedge-shaped piece may be really the 

 parietal, ankylosed at a very early period to the occipital, even before the proper elements 

 of the latter have coalesced. 



The orbit is small, oval, 6^" high and 11" long, with very prominent and distinct 

 boundaries, complete, except for a space of 1^" behind, where it is continuous with the 

 temporal fossa. This completeness and solidity of the margins of the orbit, especially 

 of the lower side, is quite peculiar among Toothed Whales [Eogia even, not excepted), 

 and depends upon the remarkable conformation of the jugal bone {j). This consists of 

 two parts, meeting at an acute angle at the prominent rounded antorbital process. One 

 (the body of the bone) is wedged in between the under surface of the orbital process of 

 the frontal and the maxillary. The other is a strong process projecting freely back- 

 wards along the inferior margin of the orbit, flattened from above downwards, and 

 gradually narrowing behind, where it articulates by an oblique surface with the under- 

 side of the end of the zygomatic process of the squamosal. This represents the styli- 

 form part of the jugal, common to the Hyperoodon and all other Toothed Whales, 

 though widely differing from it in character. 



None of the skulls examined showed any trace of a separation of the body of the 

 jugal bone into two parts, as in Hyperoodon and the Ziphioids, where one of the two 

 divisions has been taken for the representative of the lachrymal bone. It is probable 

 that the entire bone must be considered to be composed of the malar and lachrymal 

 coalesced, as in the ordinary Dolphins. 



The orbital process of the frontal is longer and nan'ower than in the Dolphins 

 generally, approaching somewhat to the form it assumes in the true Whales. The 

 supraorbital margin is much arched, and largely uncovered by the maxillary. The 

 postorbital process is strongly marked and pointed, and, as before indicated, does not 

 quite come in contact with the squamosal. The antorbital process is formed by the 

 maxillary and the jugal, being cut at its most prominent part by the horizontal suture 

 between these bones. In front of this is the deep antorbital notch. 



The side of the rostrum commences by a broad flat surface of the maxillary, a foot 

 deep, looking outwards and upwards. The borders of this gradually approximate until, 

 at about one-third of the length, they are united into a single sharp edge, much 

 upturned in the middle third, but gradually flattening towards the tip. The last 

 twenty-two inches of the rostrum is formed by the premaxillary alone. 



Base of the Skull. — This region is chiefly remarkable for the extent and massiveuess of 

 the pterygoids, although falling short of that in the Hyperoodon in this respect. They 



2 y2 



