THE MUSCLES 67 



insertion of the M. rectus cervicis profundus; (ii) a second portion 

 in which the fibres spread out, more or less fan-shaped, over the 

 floor of the mouth, into which they are inserted at the sides of the 

 tongue. 



Innervation : By the terminal twigs of the N. hypoglossus. 



Function: The contraction of this muscle must necessarily produce 

 several results according to circumstances. For example, if the 

 tongue were at rest then the muscle would tend to draw it towards 

 the front of the mouth and to arch the dorsal surface, but if the tongue 

 were fully extruded then the contraction of the muscle would tend 

 to retract it towards the mouth. Probably its main function, how- 

 ever, is to compress the glandular tissue of the tongue. This it would 

 do by drawing the tongue towards the front of the mouth under the 

 circumstances first mentioned, and the muscle would thus act as 

 a preliminary for the extrusion of the tongue by causing it to be 

 coated with a sticky mucus to which the prey may adhere. 



M. hyoglossus (m.hy.gl.) Fischer (1843); Druner (1901). 

 In Salamandra this is a small and comparatively unimportant muscle. 

 Its fibres pass from the dorsal side of the anterior extremity of the 

 copula in a posterior direction, on either side of the cartilage. It lies 

 dorsal to the anterior radials (hypohyals) and some fibres also pass 

 dorsal to the posterior radials to be inserted in the tongue, but the 

 more ventral fibres are attached to these cartilages. Driiner distin- 

 guishes the ventral fibres as the M. basiradialis. The whole muscle 

 lies deep to the M. rectus cervicis profundus, which must therefore 

 be removed to expose it. According to Driiner the muscle does not 

 exist in the larva. 



Innervation : By terminal twigs from the N. hypoglossus. 



Function: Beyond attaching the hyobranchial apparatus securely 

 to the tongue, and possibly assisting to compress the glands of the 

 latter organ, it is difficult to see what useful purpose the muscle can 

 serve. The basi-radial portion would tend to draw the posterior 

 radials antero-dorsally, and thus cause the tongue to stand up from 

 the floor of the mouth as well as to compress the mucus glands. 



M. rectus cervicis (Edgeworth). 



Pubio-hyoidien s. Pubio-glosse (partim) . , , Cuvier (1800). 



Hyoideo-ypsiloideus ...... Funk (1827). 



Sternohyoidien .... Duges (1834); Rusconi (1854). 



Sternohyoideus Fischer (1843); Owen(i866); Mivart(i869); Hum- 



phry (1872); Furbringer (1873); Walter (1887); 

 Osawa (1902}. 



