Gatty Marine Laboratory t St. Andrews. 157 



solidity is noteworthy, the pulp-cavity being largely filled 

 up, a small central canal in the massive dentine only being 

 left. The general outline of the teeth approached a spindle, 

 though the curve of the crown, especially in the maxillary 

 teeth, interferes with the regularity of such a figure. Most 

 of the teeth were flattened antero-posteriorly, and hard lines 

 occurred at the margin of the gum. The longest teeth were 

 found in the mandible, where the curvature of the crown 

 Avas less, some reaching 5 inches with a maximum diameter 

 of 1| inches. The large curved maxillary teeth measured 

 about 4s^ inches with a diameter similar to those in the 

 mandible. Almost all the teeth in this vigorous specimen 

 had two facets, from friction of the teeth opposite, on the 

 crown (one anterior, the other posterior), only one or two of 

 the back teeth being free from such injury. Moreover, some 

 had abrasions of the enamel on the summit as well as 

 externally and internally, showing that hard substances as 

 well as the opposite teeth were implicated in the abrasions. 

 The site of the main facets (anterior and posterior) varied 

 considerably, some of the anterior maxillary teeth had the 

 front facet near the gum, whilst the posterior facet was near 

 the apex of the crown. In the mandibular teeth the large 

 facet was generally in front, and the deep furrows showed 

 the force with which the powerful muscles drove the teeth 

 together. Eschricht thought that they were worn on the 

 anterior and external sides in the maxilla, but in this case 

 the facets were anterior and posterior, though it is true a 

 few presented a large abraded surface externally. This 

 character, therefore, is subject to variety. The foremost, a 

 single small tooth, in the premaxillae and mandible had fallen 

 out, and the sockets were partially filled up. It had occupied 

 the tip of each prem axilla, and another had been in the outer 

 process of each maxilla. The formidable teeth of the Killer 

 made a striking contrast with those of Glubiocephaluf, not 

 only from their solidity and size, but from the length of the 

 alveoli, viz. 15^ inches along the maxillae and the same in 

 the mandible, whereas even in a large Globucephalus the 

 rows of teeth cover but 7 inches in each case. Moreover, 

 the broad anterior region of the hard palate' with its curved 

 rows of teeth is in contrast with the longer rows of teeth, which 

 in the proportionally narrower hard palate of the Killer 

 gently diverge from each other posteriorly. 



In the mandible of Orca the symphysis slopes obliquely 

 from the front backward, and the opposed surfaces, which 

 are peculiarly smooth, are proportionally larger than in 

 Globiocephalus , in which the symphysis is perfectly straight. 



