Slade.] ^^ [March 15, 



hension, tearing and division of the flesli by means of the characteristic 

 teeth. 



In the Edentata, on the other hand, the cranium of the great ant-eater 

 exhibits a jugal arch whicli is the extreme opposite of that which has been 

 thus partially described. Here, it is very incomplete, consisting of a short 

 styliform process given off by a very rudimentary jugal, and of an ex- 

 tremely small tuberous zygomatic process from the squamosal, no union 

 being formed between the two. There is no postorbital procebs of the 

 frontal, and no separation between the orbital and temporal fossis. Under 

 these circumstanceie, the muscular development concerned in the prepara- 

 tion of the food is very feeble, correlated as it is with the entire absence of 

 teeth and any necessity for mastication. 



Between these two extreme modifications, there are many intermediate 

 forms of this arch, as will become evident as we study them in the different 

 orders of the Mammalia. 



In the PiiiMATES the arch is composed of two bones, the squamosal and 

 malar, which are joined by a serrated suture which inclines downwards 

 and backwards ; the amount of inclination being modified in the various 

 groups of this order. The strength and curvature of the arch also widely 

 vary, as does also the extent to which the various crests and ridges for 

 muscular attachment are developed. In man, the arch is generally 

 slender, slightly curved in its horizontal axis, and presents a very 

 moderate convexity upwards in its vertical curvature. Owing to the slight 

 horizontal curvature outwards, the temporal fossa is relatively shallow, 

 consequently allowing but little development of the temporal muscle. 

 This condition, however, is subject to modifications in the various races of 

 man. The maximum breadth of the cranium is at the jugal arches, and it 

 is at these points that craniologists now take the bizygomatic diameter of 

 the face. 



Humphrey, in his Human Skeleton, in speaking of this arch, says : 

 "The upper surface of its root forms a smooth channel for play of the 

 temporal muscle. In the negro the greater width of this channel throws 

 out the zygoma into stronger relief, and added to the flatness of the squa- 

 mosal portion, affords more space for the temporal muscle." This gen- 

 eral statement is not confirmed by any cranial measurements, neither does 

 Mr. Humphrey state what he means by a negro. Probably he intended, 

 as in common parlance, to designate the African, although this designa- 

 tion is ambiguous, as it is well known that the crania of the ditlerent 

 tribes of Africa differ very essentially in their general formation, as well 

 as in their special cranial measurements. 



Although the cephalic measurements of Broca, Topinard, and others 

 allow a slight increase in the horizontal curvature of the arch iu certain 

 instances, which signify a greater development of the temporal muscle, as 

 well as a more extended surface for the attachment of the masseter, yet, 

 as Topinard remarks, in speaking of the bizygomatic diameter, " This 

 measurement by itself often presents difficulties, purely accidental and 



