246 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 



of the Bovin^e are entirely unnecessary, or, being combative, provision 

 is made for purposes of offence and defence by the growth of antlers 

 or other horns. 



Thus, without further illustration, it may be said, that while it is 

 difficult in the present state of our knowledge to account for the varied 

 character and position held by cranial vacuities, or to explain why these 

 should be more . frequently present in some orders than in others, and 

 in certain genera of an order and not in others, it may nevertheless be 

 safely affirmed that whenever osseous material can be set aside without 

 interference with the general economy, or without detriment to the 

 structure of the immediate parts, it is dispensed with. This general 

 law applies to all vacuities or deficiencies, wherever situated, in the 

 crania of the Mammalia. 



Cambridge, January, 1888. 



