434 PTETtAIOTTlX. 



iiniisnnlly larpic. Tympanic ninuilar, but rather broader ihan in 



Pieropvs. Occipital and hinder parietal region eonspicnonsly 



deflented, the alveolar margin if projected backward passing 



througli base of post-tympanic process and middle of supraoccipital. 



Mandibular rami deep, symphysis broad, angular process heavy 



■witli iinusnally prominent masseteric ridge ; condyle higher above 



level of alveolar margin than in any Pteropiis (vertical from top of 



condyle to lower edge of mandible subeipial to combined length of 



all lower cheek-teeth) ; coronoid broad antero-posteriorly and steeply 



ascending, its front edge at right angle with alveolar margin. 



Dentition (figs. 21, 22). — Dental formula as in Pterojjus: — 



i^ i- c p^ p' p'' m' m^ o^ i 2 • j i i 



.—. — !— ?— ' = 34. p , m , 1,, and m, reduced. 



Upper incisors large, i^ noticeably heavier and longer than i' ; 

 posterior ledge very large, shelf-like, rendering antero-posterinr 

 equal to or greater than transverse diameter of crown ; margin of 

 cingulum of i" raised postero-intcrnalh' into a distinct obtuse cusp 

 (at least in Ft. atrata)', cutting-edge of i' obtusely, of r subacntely 

 pointed. Diastema i'^-c rather narrow, subequal to interspace c-p''. 

 Upper canine enormously thick, chieliy owing to presence of a 

 large secondary cusp halfway up its hinder edge; greatest antero- 

 posterior diameter of crown more than half (about three-fifths) its 

 length from alveolar border; inner cingulum broad, its margin 

 raised into two cusps, viz. a smaller anterior (perhaps undeveloped 

 in Ft. anceps) at base of inner vertical ridge of crown, and a larger 

 posterior opposite secondary cusp ; vertical groove on front face of 

 crown shallow or even obsolete, p' rudimentary, subequal to ij, 

 nearly styliform, crown only slightly differentiated from shaft, 

 p', p\ and m' short and broad, subsquarish ; anterior and posterior 

 basal ledge prominently developed, shelf-like with raised margin, 

 in one species {anceps) restricted to respectively ar.terior and 

 posterior portion of teeth, in the other {atrata) extending on inner 

 side of teeth ; inner longitudinal " ridge " in one species {anceps) 

 essentially Pteropine, ridge-like, in the other much shortened 

 antero-posteriorly, conical and cusp-like, m' slightly smaller than 

 p'' {cf. Pteropus : m^ with rare exceptions the largest of the upper 

 cheek-teeth), m" subsimilar in structure to m', except for com- 

 plete suppression of anterior basal ledge ; si/e as m,. 



i reduced (relatively a little smaller than in typical Pteropi, but 

 looking quite rudimentary by contrast with large i.^), subterete, 

 cutting-edge slightly bifid. \„ much enlarged, about twelve to 

 fifteen times the bulk of, and much higher than, i, ; posterior ledge 

 very long antero-posteriorly, rendering longitudinal greater tlian 

 transverse diameter of crown ; cutting-edge distinctly trifid, with 

 middle cusp much the broadest. Lower canine short and stout, 

 ciugulum forming a broad ledge at posterior base of tooth and 

 generally raised into a small rounded tubercle postero-externally. 

 p large, lower tlian, but subequal in cross section of crown to, i„ 

 which it closely resembles in structure (broad inner ledge, cutting- 

 edge trifid with middle broader than lateral cusps). Pj-m^ broader 



