PEOFESSOR FLOWER ON THE RECENT ZIPHIOID "WHALES. 221 



In general arrangement these foramina correspond very closely with those of Ilypero- 

 odmi. In the Sperm-Whale the greater massiveness of the cranial walls, compared 

 with the brain-cavity, and the consequent greater distance that has to be traversed by 

 the nerve-canals, causes some alteration in the condition of the foramina, several (as in 

 the case of that for the seventh and eighth nerves) more completely coalescing into a 

 single aperture, at least at their cerebral ends, than in the smaller-headed Ziphioids. 



Dimensions of the Skull. 



inches. 



Extreme length of cranium 54 



Length of rostrum (from the apex of the praemaxillse to the middle of 



a line drawn between the anteorbital notches) 36-2 



Anterior end of vomer to anterior end of prsemaxillae 13-6 



From middle of hinder edge of palate (formed by pterygoid bones) to 



end of prsemaxillae 43-2 



Greatest height of skull, from top of nasals to lower border of pterygoids 21 



Greatest breadth, across postorbital processes of frontals 27 



Breadth across zygomatic processes of squamosals 26-4 



Breadth between outer borders of suprafrontal processes of maxillae . . 24'6 



Breadth of occipital condyles 7 "5 



Breadth of foramen magnum 2 '4 



Height of foramen magnum 2'5 



Breadth of exoccipitals 20-5 



Breadth of base of rostrum (between bottom of anteorbital notches) . .15-7 



Breadth of rostrum at middle 6 



Nasal bones, antero-posterior length 5-2 



Nasal bones, greatest breadth of the two 4 



Anterior nares, greatest width of the two 2-9 



Breadth between outer borders of praemaxillse opposite nares .... 6-6 

 Breadth between outer borders of prsemaxillae at theu- widest part, in 



front of the nares 8'2 



Breadth between outer borders of praemaxillee at middle of rostrum . . 3-6 



Mandible. — Length of ramus 49 



Length of symphysis 12-2 



Vertical height of ramus at coronoid process 8-3 



Apex of mandible projecting beyond apex of rostrum . . 2-7 



The rami of the mandible are not ankylosed at the symphysis. They are more 

 massive in form and of a denser substance than in Hyperoodon, especially near the 

 symphysis, corresponding with the greater development of the teeth. A slight irre- 

 gular groove, with numerous minute vascular canals opening into it, extends along the 



2k2 



