OF THE TONGUE OE PAEEOTS. 237 



greater extent. In Calyptorhynchus funereus (probably also in C. banJcsii, where the 

 muscle was injured before the tongue came into my possession), CacaMia alba, Cacatua 

 triton, and Nasiterna the muscle is similar to that in Psittacus. In Nasiterna, how- 

 ever, the twig {th.g^.) does not become confluent with its fellow of the other side, but 

 lies, with no definite attachment in the entoglossal cavity, just beneath the membrane 

 of the tongue. In Cacatua triton the twig of either side also branches at its extremity, 

 which thus becomes bifid ; this condition foreshadows the peculiar one seen in 

 Pceocejjhalus I'iijjpelli and Ptistes (Plate XXVI. figs. 6 & 10). In Cacatua 

 sul'phurea (text-fig. 8) the twig is continuous with a trifurcate tendinous structure, one 



Text-fiK. 8. 



Cacatua sulpJiurea.—Dorsa.l view of thyroglossus. Semi-diagrammatio. (Nat. size.) 



E. = entoglossum. 

 T. == trachea. 

 P.P. = apex of parahyal process. 

 ih.tj. = larger outer branch of thyroglossus. 

 thg\ = smaller inner branch of thyroglossus, which on the 

 right-hand side was injured in dissection, 

 a, /3, 7 = tendinous branches of tli.g^. 

 (J. = glottis. 



prong («) of which is attached to the entoglossal of the same side of the tongue, one (/3) 

 to the entoglossal of the other side, and the other (y) to the parahyal process of the other 

 side. Doubtless there is a similar arrangement for the muscle of the other side, but 

 it was unfortunately injured in dissection. To some extent this condition is similar 

 to that in Pceocephalus and Ptistes ; but I prefer to place it in this stage rather than 

 with either of them, because the aforesaid tendinous prolongation of the muscular twig 

 is not such a definite structure as that which apparently represents it in them, and 

 may probably be an individual variation. 



