8 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 70 



falcate processes extend ventrad of the floor of the basioccipital, and 

 apparently infinite variety in the development and shape of the lat- 

 eral border of the exoccipital. The most important detail of this 

 variation, from a functional standpoint, is the distance from the 

 condyle to the lateral border of the exoccipital, the difference ex- 

 hibited being as great as 20 mm., thus altering by just this degree 

 the leverage of the attached muscles. Worthy of note is the smooth- 

 ness of the occipital region as a whole and the large capacity of the 

 brain case. There is a great variation in the intercondyloid portion 

 of the basioccipital, as in 240003 this measures 8.5 mm., and in 



BIVENT. CEW 

 COMPLEXU' 

 VJDNt ChP. + Z'i.V.M.^^ 



^^^STo•.«JN^E.R 



^CALENU«i DORS.' 



V BUCUNKTOR. 



A\N?..S.VJPm,T\c/ 



Fig. 2. — Lateral aspect of right side of the skull of neombris, 



SHOWING partial DISSECTION OF SUPERFICIAL RESPIRATORY SAC (ARROW 

 1 POINTING TO ITS PASSAGE OF COMMUNICATION WITH THE BLOWHOLE) ; 

 THE SECOND LAYER OF SPIRACULAR MUSCULATURE ; AND ATTACHMENTS OF 

 THE MUSCLES TO THIS PART OF THE SKULL 



240002, 20 mm. in width; but in these two specimens the total con- 

 dyloid width is approximately equal. The bone of the more central 

 portion of the basioccipital is so thin that in 240001 and 240003, and 

 to a lesser extent in 240002, there are extensive vacuities here. 



Measurements of cranial details {hi millimeters) 



