40 



ELEMENTS OF MAMMALIAN ANATOMY 



the palatine and orbitosphenoid, is the orbital plate of the 

 frontal. 



In the majority of the Mammalia the frontal is a paired 

 bone, but in man the two portions become anchylosed during 

 the fifth or sixth year. The horns of ruminants are out- 



FiG. 17. — Dorsal Aspect of the Cat's Skull. 

 ap. Anterior palatine foramen; c, canine tooth; co, coronal suture; /, foramina 

 in palatine bone, the lateral one is the posterior palatine and the medial one is 

 the sphenopalatine; fr, frontal; if, infraorbital foramen; in, interparietal; Ic, 

 lachrymal canal at the medial border of the lachrymal bone; Id, lambdoidal 

 crest; ml, malar; mx, niaxillary; na, nasal; oc, occipital; p, vertical plate of the 

 palatine; po, postorbital process of the frontal; pm, postorbital process of the 

 malar; par, parietal; px, premaxillary; sq, squamosal part of the temporal; sg, 

 sagittal suturo; sp, alisphenoid part of the sphenoid; Ip, temporal fossa; ag, 

 zygomatic process of the squamosal. 



growths of these bones. Among the Cervidse (deer) horns are 

 usually developed only on the male, and are shed every year. 

 In the Bovida.^ (cattle) the horns are permanent when present. 

 The ethmoid (Fig. 19) is a single bone lying ventral to the 

 frontals and nasals. It separates the cranial cavity from the 

 nasal cavity and projects into the latter in the form of two 

 thin scroll-like plates of bone and a median vertical plate. 

 In order to see the relations of this bone, three skulls must be 



