44 2 Bulletin American Museum of Natural History. [Vol. XX, 



Cranial Measurements. 



15459 23471 i546o x 23473 23472 

 56$?? 



Total length 89 85 82 79.5 84 



Basilar length 78 74 70 65 67 



Zygomatic breadth 49 50 50 46 



Nasals, length 30 30 29.5 25.5 30 



" breadth anteriorly 21 20 19 18.5 19 



posteriorly... 23.5 21 21 21 19 



Interorbital breadth 33 32 32 31.5 29 



Depth of skull anteriorly 40.5 37 37 35 36 



" occiput 22 23 23 21.5 22 



Diastema 23 22 20 19 20 



Length of palate 39 39 35 32.5 35 



" " upper toothrow. ... 20 19.3 19 17.5 18 



Coendou sanct&marta is a small form of the C. prehensilis 

 (' Synetheres') group, but differs from C. prehensilis, C. brandti, 

 and C. centralis in being about one third smaller than either 

 of the three forms and very differently colored, the spines 

 being much more narrowly tipped with white, the basal white 

 portion narrower, and the dark portion much broader, so that 

 the general coloration of the dorsal area is blackish punctated 

 with white, instead of white varied with black, or black and 

 white about equally mixed. The males are much larger than 

 the females, but the largest male skulls are very much smaller 

 than even the smallest skulls of the C. prehensilis group. 



The series of 5 skulls of C. sanct&marta show great variation 

 in the amount of inflation of the frontal region of the skull. 

 In No. 15459 ($ ) the front third of the nasals is nearly flat, 

 but at the posterior border of the front third they rise abruptly 

 to meet the greatly inflated frontals, this enormous inflation 

 involving also the width of the posterior arm of the premaxil- 

 laries. In Nos. 23473 ( ? ), 23472 ( $ ), there is also considera- 

 ble inflation of the frontal region, but in the other two skulls 

 (including the type) there is very little, the nasals and frontals 

 being nearly as flat as in the Spiggurus group. For this 

 reason it seems impossible to differentiate satisfactorily forms 

 in a group subject to such an extraordinary amount of indi- 

 vidual variation in the form of the skull as is evident in the 



1 Type. 



