SKULL OF LUTRA CANADEXSLS. 305 



occipital behind; it is already partly contluent with the periotic. 

 The basilar suture is distinct, directly transverse, near the an- 

 terior end of the bulbil. Similarly, the spheno-vomerine suture 

 is open ; it appears back of the end of the palate. The ptery- 

 goids are already lost in the sphenoid, but the pterygo palatal 

 suture is evident, opposite the spheno-vomerine. The contour 

 of the palatine bones may be traced all around, though their 

 palatal plates are fused with each other. The maxillo-palatine 

 suture is opposite the anterior portion of the last premolar. The 

 palatal plate extends far backward, as already twice indicated 

 in noticing otiier points, and its orbital portion curves over into 

 the temporal fossa, though it forms but an insignificant portion 

 of the orbit proper, being only prolonged by a slight process 

 fairl3^ into the orbit. The orbito-sphenoid remains instruct- 

 ively distinct from all surroundings, bounded above and in 

 front by the frontal, behind and partly below by the alisphe- 

 noid, for the rest below by the palatal. The lachrymal is 

 similarly distinct, except anteriorly. The malar is seen to form 

 most of the zygomatic arch ; though the pointed process of the 

 squamosal overlies it nearly half-way, its bevelled i^osterior 

 extremity reaches almost to the glenoid fossa ; its anterior ex- 

 tremity runs along on top the maxillary to the lachrymal, form- 

 ing an upper layer of the bridge over the auteorbital foramen. 

 The palatal plates of the intermaxillaries extend in a V past 

 the canines to a point on the median line opposite the second 

 premolar; the incisive foramina are not pierced entirely in these 

 bones, their posterior periphery being completed by a nick in the 

 corresponding border of the palatal pl'ate of the superior 

 maxillary. 



Eeturning to the adult skulls for examination of the mandi- 

 ble, we find that this bone has a stout thick ramus, with long 

 slanting symphysis, an irregular continuous curve from incisors 

 to angle, with a slight emargination just in advance of the 

 latter, and a rather low broad obtuse coronoid, the front border 

 of which is nearly straight and vertical, the posterior border 

 curving forward with quite an elbow^ to the apex. The condyle 

 is wide across, but narrow in the other direction ; it slants 

 oblique both to the horizontal and vertical plane, its inner end 

 being both higher and further back than the other. There is 

 a deep notch between the condyle and angle of the jaw, which 

 last is not exflected. The muscular impiession on thi' outside 

 of the jaw is, as usual, well marked; it ends below in a rounded 

 outline beneath the 1-ist molar. 

 20 31 



