30 THE MYOLOGY OF THE RAVEN. 



If these muscles contrcact in unison, the hirynx being 

 the fixed point, they will evidently depress the tongue. 

 Acting singly in the same way, either one will likewise 

 depress the tongue, but also giv^e it a lateral deflection to 

 the side towards the muscle which is contractino;. 



If they contract together, with the base of the tongue 

 as the fixed point, they will pull the larynx forwards, a 

 very necessary movement during the accomplishment of 

 the act of deglutition. 



26. The depvessor-glossus is the name 1 have bestowed 

 upon a small but important muscle which Professor Owen 

 describes in the following words: "A small and short 

 muscle, which is single or azygos ; it passes from the 

 basihyal to the under part of the glossohyal ; it depresses 

 the tip of the tongue and elevates its base" {loc. cit., 

 p. 154). Nameless though he left it, Professor Owen's 

 description answers very well indeed for a corresponding 

 muscle that we find in the Raven, and the one, as I say, 

 I propose to call the depressor-glossus. In this bird it 

 arises fleshy over the entire under surface of the first 

 basibranchial (basihyal of Owen), the fibres contract as 

 they pass forwards, and become tendinous between the 

 tongue bones, and as a delicate tendon so continue on to 

 finally find an insertion at their tips, where they meet 

 anteriorly (Fig. 17). When tliis muscle contracts, the 

 tongue must behave in a manner already described, and 

 quoted from the authority above. 



27. The cerato-glossus is a small muscle we find on 

 the upper side of the hyoid, one on either cornua. Each 

 occupies, as an origin, the half of the surface of the first 

 basibranchial. After passing over the joint formed by 

 the head of the thyro-hyal, the fibres become more 

 tendinous, as they insert themselves along the upper 

 side of the shaft of the cerato-branchial element. They 



