874 



SKULL 



as 'proc. zygomaticus, is very variable in size, being largest in the 

 Ostrich, Gallinai and Parrots, and smallest in Anseres. In many 



Galllnx both pro- 

 cesses meet at their 

 distal end and trans- 

 form the temporal 

 fossa into a foramen. 

 The Periotic 

 Bones, enclosing the 

 inner Ear (p. 178) 

 occupy a space 

 bounded beneath 

 by the Basioccipital 

 and Basisphenoid, 

 in front by the Ali- 

 sphenoid and Scpia- 

 mosal (which last to 

 a great extent over- 

 laps and hides them 

 when viewed from 

 without), behind and 

 above by the lateral 

 and supra-occipitals 

 and parietals. The 

 Periotics consist of 

 three distinct ele- 

 ments, which in size, 

 relatiA^e position and 

 in regard to the sur- 

 rounding bones ex- 

 hibit many modifi- 

 cations, forming a 

 very difficult chapter 

 of ornithic anatomy 

 which as yet has been touched by few,^ though an exhaustive study 

 of them promises results of prime taxonomic importance. The 

 Prootic (Petrosal of some writers) abuts upon the Alisphenoid, and 

 with the latter encloses the foramen ovule, through which passes the 

 3rd branch of the nervus trigemmHS,whi\e between the posterior margin 

 of the Prootic and the anterior border of the Lateral Occipitals lies 

 the fe7iestra oralis,^ into which fits the base of the Cohimdla of the ear, 

 and the fenestra rotunda. Dorsally the Prootic adjoins the Epiotic 



^ Among them are the late Prof. "\V. K. Parker in several of his numerous 

 papers, Prof. Huxley in his Elements of Comparative Anatomy and Prof. Selenka 

 (Bronn's) Thier-Eeich. 



^ Inadvertently called foramen ovale on p. 179. 



SJo, 

 Skull of Common Fowl from beneath. (After Parker.) 



