XXX11 



INTKODITCTION. 



Tig. 15. 



(From P. Z. S. 1895, p. 392, fig. 16.) 



■33 



<*& 



Dorsal aspect of mandible. 



a. Articular prominence. 

 ag. Angular process. 

 rjrj. Fossa for genioglossus. 



ia. Internal articular process. 

 pa. Minute rudimentary prominence representing 

 a post-articular process. 



The hyoid of the Psittaci from Psittacus erithacus to Stringops habroptilus (inclusive), 

 so far as I have been able to ascertain, presents characters which separate off the Parrots 

 from every other Order of Birds. 



The common but distinctive characters of the Psittaci. consist in their possession of: — 



(1) A basihyal which is much broadened out posteriorly (b). 



(2) A process, named * parahyal process (p), which projects forwards and upwards 



from either side of the basihyal. 



(3) An os entoglossum in the form of a single broad bone with a considerable central 



foramen or, more commonly, in the form of two lateral parts, entoglossals, 

 medianly united in front by cartilage, and leaving a vacant space between this 

 and their attachment behind to the basihyal. 



In the Loriidce which I have been able to examine, so far as I know, the three parahyal 

 processes are very long and slender, and pass forwards, curving gently mesiad, till they meet 

 in a symphysis and so constitute a parahyal arch (figs. 17, 18, & 19, p). 



* See P. Z. S. 1S95, p. 162. 



