ZEUGLOBONT A^D OF LEATHERY TURTLE. 31 L 



Prozeuglodon or Zeuglodon. I., follows immediately beliind I^, but 

 between it and I., there is interval of about 23 mm. The canine 

 is separated from I., by a diastema of 30 mm. ; it is represented 

 by its broken base, which shows that it was about the same size 

 as I.„ and was probably somewhat compressed from side to side 

 Avith an anterior angle ; like the incisors it was directed forwards. 

 Behind and a little to the outer side of the lower canine there 

 is a slight depi^ession in the outer surface of the jaw, presumably 

 for the reception of the point of the upper canine. Pm^ is 

 represented by the anterior lialf of its broken base in specimen B, 

 and by its socket only in specimen A •, it is separated from the 

 canine by an interval of about 45 mm., and was considei'ably 

 compressed laterally, its long diameter being about 30 mm., the 

 transverse only 14. The i-emaining teeth are nil represented in 

 one or other of the specimens by their more or less broken crowns. 

 Pm., is preserved in specimen A onl}'^, where it is present on both 

 sides, following pm^ at an interval of 19 mm. It is a two-rooted 

 tooth, the greatest length of which is 37 mm., while its greatest 

 width above the front of the posterioi- root is 13 mm. So far as 

 can be made out, the compressed crown formed a single cusp 

 without accessory serrations. Both the anterior and posterior 

 borders of the crown are blunt and rounded ; at the base of the 

 crown there is a well-marked constriction and on the inner side 

 there is a slightly developed cingulum. The enamel is much 

 roughened, being raised into knotted ridges, which for the most 

 part run vertically. On the posterior lobe of the tooth the 

 enamel ridges of the outer and inner side meet, forming a keel 

 which is situated rather more on the inner than on the outer 

 side of the crown. 



Pm^ is represented in specimen B by its roots only, but in 

 A is present on both sides, that on the left being nearly 

 complete. It is a, long, laterallj^ compressed two-rooted toothy 

 the length of the crown being 53 mm., its greatest breadth only 

 15 mm. The crown forms one large cusp, the anterior slope of 

 which is shorter and steeper than the posterior. On the anterior 

 border there seem to have been no accessory cusps, but on the 

 postei'ior there are two with perhaps a. rudimentary basal cusp 

 just above the cingulum, which is well developed on the postero- 

 internal side ; it is also distinctly marked on the outer and less- 

 clearly on the inner face of the tooth. The summit of the main 

 cusp has undergone considerable wear, which also extended down 

 the anterior edge ; the top of the upper accessory cusp is also 

 worn . 



Pm, is unfortunately represented in specimen B by its two 

 roots only, while in A the crown is very imperfect. It was even 

 moi-e strongly compressed laterally than pm.j, and from before 

 backwards was considerably the longest tooth in the series, 

 measuiing 59 mm. in this direction, while from side to side the 

 greatest width (al;ove the posterior root) is only 18mm. It 

 consisted of a main anterior cusp, which may or may not have 

 borne small accessory cusps, and a posterior heel-like cusp which 



