CHAPTER XIII. 



THE SKULL IN THE EDENTATA, MARSUPIALIA, AND 

 MONOTREMATA. 



Order Edentata. — The different families of this hetero- 

 geneous group present some remarkable variations in their 

 cranial characters. 



One of the most extremely modified forms is the Great 

 Anteater {Myrmecophaga jubata. Fig. 65). The whole skull 

 is very greatly elongated and narrow, and its upper surface 

 smooth and cylindriform. The occipital plane slopes upwards 

 and forwards. The parietals are narrow, but the frontals much 

 elongated. The olfactory fossa of the cerebral cavity is very 

 large ; the cribriform plate greatly expanded, and the ethmo- 

 turbinals much developed, and consisting of very numerous, 

 delicate lamellae. Anteriorly, the face is produced into a 

 very long, tubular rostrum, rounded above and* flattened 

 below, and with terminal nares. This rostrum is composed 

 of the mesethmoid, ossified for more than half its length, 

 the vomer, the maxillae, and the long and narrow nasal 

 bones ; the prem axillae (PMx) being extremely short and 

 confined to the margin of the anterior nares. There are no 

 teeth in either jaw. The zygomatic arch is incomplete, the 

 styliform malar {Ma) only articulating with the maxilla in 

 front, and not reaching the very short zygomatic process of 

 the squamosal (Sq). The lachrymals (Z) are distinct, and 



