OF THE TOXGUE OE PAEEOTS. 213 



tongue : Psittacus leucocepJialus, Microglossus aterrimus, and Ara macao were alone 

 dealt with, and the account being comparative and incorporated Avith the description of 

 the lingual myology of other birds, does not attempt to deal with the subject in an 

 exhaustive or detailed manner. 



In 1893, he (4') divided the Parrots into two families, i.e., Trichoglossida3 and 

 Psittacidse, basing his classification upon the external characters of the tongue, viz., the 

 presence or absence of horny fibres [Ilornfasern), the completeness or incompleteness 

 of the orbital ring, and the direction of the file-like markings on the upper beak. 



In 1895 and 1896 St. G. Mivart (6 & 7) published some very complete descrip- 

 tions of the hyoid bones of various Parrots, and among others described and figured 

 for the first time those of Lorius clGinice/la, Lorius flavo-palliat,us, and Eos reticulata. 

 In this paper atteution is directed to certain bony ])rocesses of which no previous 

 records exist, and the relationships of these to certain muscles of the tongue I 

 describe in the body of this paper. 



Mivart further showed that the Order Psittaci is distinguished from every other 

 order of birds by the shape of its hyoid, and that the characters which determine this 

 are as follows : — 



1. The posterior enlargement of the basihyal. 



2. The growth upwards and forwards of a process on either side of the basihyal, 



which he proposed to call the parahyal process. 



3. The presence of an os entoglossum (ceratohyal of Shufeldt) in the form either 



of a single broad bone with a considerable central foramen, or, much more 



commonly, of two lateral parts (entoglossals), which are united in their 



anterior middle region by cartilage so as to leave a space between this and 



their attachment to the basihyal. 



He concluded that, among the Psittaci, the Loriida; present a very distinctive 



character, in respect of the growth forward of the parahyal processes and their union 



in the middle line to form the parahyal arch ; and in the course of this paper I am able 



to substantiate his conclusion, by the discovery that, in respect to their lingual muscles, 



the Loriidse also present distinctive characters, in reference to which they appear to 



occupy an isolated position. 



In 1893 Beddard and Parsons (5) called attention to certain points of similarity 

 in the myology of Parrots, and directed attention to the existence of differences in the 

 arrangements of the tendons of the tensor patagii muscle. Their observations led 

 them to the conclusion that " the patagial tendons of Psittacus closely resemble those 

 of Chrysotis " ; and this is corroborated by certain facts embodied in the present paper, 

 which show that a similar agreement exists between the two birds, in respect of a lingual 

 muscle which, within the range of Parrots so far studied, exhibits certain modifications. 

 The outcome of the present investigation shows that the lingual muscles of Parrots 

 are in the course of evolutionary changes, some of the muscles exhibiting the structural 



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