22 INTRODUCTION. 



squamous portion, c ; to which is articulated the tympanic 

 portion, or os quadratum, d. The parietal bone, e, intervenes 

 between the occipital and the frontal. The latter, /, besides 

 forming the anterior part of the covering of the brain, also 

 constitutes the upper edge of the orbit or cavity in which the 

 eye is lodged, its posterior process, ^, bounding it behind, while 

 its antorbital process, /i, margins it before, and is connected 

 with the lachrpiial bones. The lower part of the orbit is 

 thus left incomplete, as it is in various degrees in all birds, ex- 

 cepting some of the parrots. The sphenoid bone is originally 

 composed of several distinct parts : a basilar portion, united to 

 that of the occipital bone ; two orbital plates, /, constituting 

 part of the orbits and of their septum ; two cranial plates, /, 

 corresponding to the wings, and forming the posterior part of 

 the orbits ; and two pterygoid or interarticular portions, k, 

 which are articulated posteriorly to the tympanic bones. The 

 ethmoid bone forms the anterior portion of the septum of the 

 orbits, /, and separates them from the cavity of the nose. Ex- 

 cepting the OS quadratum, c?, and the pterygoid process of the 

 sphenoid bone, k, these bones are all anchylosed or united in 

 the Raven and other Crows, as is indeed the case with most 

 adult birds. 



The Face is primarily divided into the upper jaw, m^ formed 

 of a number of bones, and the lower jaw, ??, formed of a single 

 bone. The nasal bones, o, occupy the basal part of the upper 

 jaw, and bend obliquely downwards behind the nasal cavity. 

 The lachrymal bones, j9, are articulated with the antorbital 

 process of the frontal bone, h, the nasal, o, and the malar 

 bones. The latter, q, are here articulated posteriorly with the 

 lachrjTnal bones, anteriorly and above with the nasal, and 

 below with the long slender process of the upper maxillary. 

 The intermaxillary bones, r, form the greater part of the 

 upper mandible, extending from its extremity along the ridge 

 and sides, and are united with the superior maxillary bones. 

 The latter, 5, are generally small. They send a long slender 

 process, t, backwards, along the edge of the upper mandible, 

 to be articulated to the tympanic bone, 3. This process is by 

 some considered as analogous to the zygomatic arch, and 



