146 SHUFELDT. [Vol. XVII. 



departure agrees with such other differences as are to be found 

 in the structure of the crania of the two species under consid- 

 eration. The flap is 13 mm. wide, and the posterior integu- 

 mental fold about 8 mm. ; the height of the ear-slit in an adult 

 male specimen (collected at Hamar, May 23, 1880) is, as in 

 A. accipitrimcs, about 35 mm. The nostrils, the structure of 

 the beak, and its relation to the total length of the cranium 

 are identically the same as in A. accipitrhitis . The cranium 

 likewise, in the main, agrees with the cranium of A. accipi- 

 t rimes. 



Its pointed, triangular form is here even better marked, 

 inasmuch as the obliquely sculptured part of either frontal is 

 more extensive and reaches further backwards. The greatest 

 vertical height of the cranium is found in the posterior orbital 

 region. 



The superior surface exhibits the same median furrow as in 

 A. accipitrimis. The orbits are comparatively even of less 

 diameter than they are in A. accipitrimis, due to the fact that 

 their obliquely sculptured portions at their posterior borders, 

 which are contributed by the frontal bones, are, in the present 

 species, more extensive than in A. accipitrimcs. 



The longitudinal diameter of the postorbital part of the cra- 

 nium is here almost as great as is the diameter of the orbit ; in 

 A. accipitrijiiis it is considerably less. 



The osseous crest of the alisphenoid {proc. orbit, post.) is 

 notably small and narrow ; while the apophysis upon its poste- 

 rior surface (at least in the specimens examined by me up to 

 the present time) is either rudimentary or absent. The frontal 

 region is somewhat broader than it is in A. accipitrimis ; its 

 width is greater posterior to the supraorbital processes than it 

 is in front of them, while the reverse of this is the case in 

 A. accipitrimis. 



The frontals form at the posterior borders of the orbits, as 

 in A. accipitrimis, a slanting surface, which is abruptly trun- 

 cated both above and below ; but this surface is deeper than in 

 the species named, inasmuch as its height is equal to the length 

 of a pterygoid bone. The interorbital septum is transversely 

 thick, as in A. accipitrimis, and, as in the species named. 



