764 PROFESSOR TURNER ON ZIPHIUS CAVIROSTRIS 



transverse diameter. This surface was in the hollow of the beak, and formed 

 indeed a part of the posterior boundary of the floor of the great pre-nasal fossa. 

 It was separated by a suture from the vomer, and the distance between this 

 suture and the posterior truncated end of the meso-rostral bone was 6f inches. 

 The smoothness, not only of the truncated surface of the meso-rostral bone, but 

 of the expanded anterior border of the ethmoid, induced me to think that the 

 bar of cartilage, which had undoubtedly connected them together in the young 

 state of the skull, had either altogether, or to a large extent, disappeared prior 

 to maceration. For in the skeletons of the Cetacea when unossified cartilage is 

 continuous with the end of a bone, the surface of bone in apposition with the 

 cartilage possesses a faintly tuberculated appearance, such as one is familiar 

 with on the attached surface of an epiphysis of a human bone. 



The vomer formed the anterior part of the floor of the pre-nasal fossa, and 

 passed backwards to embrace the inferior border and the sides of the mes- 

 ethmoidal part of the nasal septum. The backward prolongation of the vomer 

 on the left side of the mes-ethmoid was partially concealed by short yet strong 

 bars of bone connecting the left pre-maxilla with the mes-ethmoid. The 

 posterior or cerebral surface of the mes-ethmoid was expanded laterally, and 

 instead of being perforated into a cribriform plate, possessed only a single 

 foramen on each side, in all probability for the transmission of a nasal branch 

 of the fifth cranial nerve. 



The superior maxilla formed the side of the beak, but did not extend to 

 within 2^ inches of the tip. For some distance backward it was a compara- 

 tively narrow bar of bone, having a deep furrow along its line of articulation 

 with the pre-maxilla ; but opposite the large maxillary foramen it expanded 

 both vertically and transversely, overlapped the anterior surface of the frontal, 

 and formed a deep maxillary fossa immediately to the outer side of the upper 

 and posterior end of the pre-maxilla. The free surface of this part of the bone 

 was pitted with irregular shallow depressions, and perforated by a large canal. 



An ecto-maxillary ridge, faintly grooved at its free border, extended along 

 the outer edge of the maxilla, and at the base of the beak was elevated into a 

 maxillary tuberosity, sufficiently large to form a noticeable feature in the profile 

 view of the cranium. The maxillo-premaxillary furrow extended backwards 

 immediately to the inner side of this tuber to become continuous with the 

 deep maxillary fossa, and the large maxillary foramen opened into it at the 

 inner side of the tuber. In Globio-cephalus, and in various others of the 

 toothed whales, the pre-maxilla does not so completely overlap the superior 

 maxilla, but that a portion of the latter bone appears on the surface to the 

 inner side of the pre-maxilla, and intervenes between it and the nasal. In Z. cavi- 

 rostris, on the other hand, owing to the incurvation of the pre-maxilla, the 

 portion of the superior maxilla above referred to was thrown into the outer wall 



