1895.] HTOID BONE OF CERT.ilK PAREOTS. 163 



"always short, usually extending forwards from its attachment aa 

 well as backward," adding that " the forward production often 

 unites with its fellow, so as to form the basal part of the direct 

 support of the tongue." 



Each entoglossal does project both more or less backwards as 

 well as forwards from its place of attachment to the basihyal, and 

 this may indicate that it includes a ceratohyal element, but it must 

 surely represent the glossohyal also. This question I will not, 

 however, now attempt to determine. 



That the Parrots should have a tongue-bone of exceptional form 

 is, of course, only what was to be expected from the exceptional 

 form of their tongue as a whole. 



I will now first describe the hyoid of Psittacus erithacus as a 

 type, then those of the three genera of Lories and that of the 

 genus Strincjops. 



Psittacus erithacus. (Fig. 1, p. 164.) 



The hasihyal is narrow for rather more than its anterior half, 

 expanding slightly both laterally and vertically towards its extreme 

 anterior end, where there is a saddle-shaped surface (for the ento- 

 glossum) convex transversely and concave vertically. Its ventral 

 Hp projects forwards much more than does its dorsal lip. Ou 

 the dorsum of the basihyal at its anterior end is a slight, though 

 marked, concavity (c). The posterior part of the basihyal expands 

 into a subquadrate plate, the centre of which is traversed by a 

 strong antero-posterior ridge continuous with the transversely 

 convex upper surface of the narrow anterior portion of the bone. 

 From each antero-external angle of the quadrate plate of the basi- 

 hyal a marked parahyal process (p) extends forwards, upwards, and 

 slightly outwards, then 7iarrovving to a bluntish point which in- 

 clines inwards as well as upwards, the whole parahyal process on 

 each side beiug more or less curved. 



The ventral surface of the basihyal is also strongly convex from 

 side to side at its narrow portion and also along a ridge which 

 thence continues ante ro-posteriorly across its expanded part and on 

 into the urohyal. On either side of this median ridge the under 

 surface of the expanded part is gently concave. 



The hinder border of the basihyal, on either side of its continu- 

 ation into the urohyal, presents an elongated articular surface, 

 concave transversely, slightly convex dorso-ventrally, for junction 

 with the Tiiipohranckial. 



The urohi/al is one with the basihyal and continues on without 

 change of direction, tapering a little, to its somewhat blunt, slightly 

 enlarged termination, which is tipped with cartilage. Its dorsal 

 margin appears slightly concave antero-posteriorly, when the uro- 

 hyal is viewed in profile. Its length is three-quarters the length 

 of the basihyal. 



T^he entoglossum consists of two lateral parts (entoglossals), which 

 meet together to articulate with the saddle of the basihyal and so 

 form a Uttle transverse isthmus of bone, whence each entoglossal 



11* 



