THE RABBIT. 257 



nerve endings can come into contact with the air corre- 

 sponds with the keen sense of smell possessed by the 

 rabbit. 



The lachrymal bone of each side forms a large part of 

 the anterior wall of the orbit, and joins the frontal by a 

 suture above. 



The squamosal bones form the greater part of the con- 

 vex lateral walls of the cranial cavity, and send out a 

 stout lateral process to form part of the posterior border 

 of the orbit. The flattened bars of bone which connect 

 this process of the squamosal with the corresponding 

 backward process from the maxillary, and complete the 

 outer border of the orbits, are the molars (or cheek bones). 



Two (composite) bones remain to be found on the 

 median ventral surface of the cranium. These are the 

 basisphenoid, which has a triangular body (seen from 

 below) and two flattened, wing-shaped, lateral processes, 

 and which is situated immediately in front of the occip- 

 ital ; and the presphenoid, a narrow bone in front of the 

 basisphenoid, extended upward into a thin median plate 

 between the orbits, and perforated by the interorbital 

 foramen. 



The pterygoids are two narrow, vertical plates of bone, 

 attached to the base of the skull at the lateral junction 

 of the two sphenoids. Each has a free posterior border, 

 which ends below in a curved process. 



The palatines are two nearly vertical plates of bone, 

 which extend forward from the pterygoids, form the 

 lateral walls of the posterior nasal opening, and meet each 

 other on the median line of the roof of the mouth by 

 horizontal platelike processes. 



IV. Shoulder Girdle and Arm Bones. In the shoulder 

 girdle the three usual bones of each side may not be at 

 first recognizable. The scapula is a large, flat, triangular 

 bone, expanded at the end which forms the apex of the 



NEED. ZOOL. 17 



