OF TKS TONGUE OF PAEEOTS. 



229 



In Ara ararauna (text-fig. 6) the muscle is like that in Cacatua galerita, but it 

 passes over the basihyal without forming an origin from it. In Ara macao the muscle 

 is similar to that in A. ararauna, but the two halves are distinct right up to their 

 insertion and a rudimentary bifid tendon is present (PI. XXVII. fig. 20, cg.s.). 

 In Microglossus aterrimus it is like that in Ara ararauna, but there appears to be 

 an additional insertion to the dorsal concavity of the rounded anterior extremity of 



Text-flg. 6. 



H.B.- 



C.B-^ 



Ara ararmina.—Doics^l view. The trachea, thyrohyoideiis and thyroglossus have been removed, and upon 

 the right, also the stylohyoideus and sternohyoideus and a part of the anterior portion of the meso- 

 giossus, in order to show the rounded cartilaginous extremity of the entoglossum, over which the sheath 

 of the muscle works. (Jfat. size.) 



B.H. = basihyal. 

 C.B. = cerato-hranchiul. 

 E.N. = entoglossum. 



Additional letters. 



hg.o. = hypoglossus ohliquus. 

 sJi. = stylohyoideus. 



st.li. = sternohyoideus. 

 U.K. = urostyle. 



the basihyal, which lies immediately ventrad of the usual insertion [cf. Mivart, 

 P.Z.S. 1895 and 1896). 



In Chrysotis ochrocephala (PI. XXVII. fig. 12) and Beroptijus accipiirinus the 

 muscle is similar to that in Cacatua galerita, but its origin along the hypobranchial 

 is not quite so extensive, and anteriorly it receives on either side a small bundle of 

 fibres arising from the ventral surface of the hyoid, and which appears to be a portion 

 of the hypoglossus obliquus forming a new connection. In Chrysotis {viridigenalis) 



2h2 



