OF THE TONGUE OF PAEEOTS, 247 



(/3) Ilypoglossus rectus. — This muscle (hg.r.) arises from the outer surface of the 

 posterior lateral j^rocess of the entoglossum and is inserted tendinous partly into the 

 apex of the tongue and partly into the fascia of the mesoglossus (PL XXIX. fig. 50). It 

 exhibits but very little variation, and such as it does consists in the length and breadth 

 of its insertion tendon and in the single or paired condition of that. In the majority 

 of Parrots the tendon of each half of the muscle is confiaent with its fellow of the 

 other side ; but in a few [Lorius, Eos, Ara ararauna) it is double. In Lorius domicella 

 the tendon is narrow but thick, and tends to be cylindrical in form. It appears to be 

 a muscle that works in conjunction with the mesoglossus, partly in the working of the 

 " brush " of the tongue in the Lories and Nestor, and partly in depressing the apex of 

 the tongue in all. The tendon of the muscle moves over the rounded cartilaginous 

 extremity of the entoglossum. 



In Nestor (PI. XXIX. fig. 46) both the muscle and its tendon are very long, a 

 condition which is correlated with the great length of the entoglossum. In Stringops 

 (PI. XXVIII. fig. 26), as in a few others, it is muscular up to its insertion, but the 

 fascia is quite tendinous in the middle of its length. 



Mvf.oHYoiDEUS Muscle. 



(a) Mijlohyoideiis anterior. — This muscle consists of two parts — a usually wider, more 

 superficial anterior (PI. XXVI. fig. 5, mh.a.) and a deeper posterior portion (mh.a^.). 

 The two parts arise from a common origin at the antero-dorsal corner of the rami of 

 the lower jaw (text-fig. 10, p. 248), just behind the line that marks the posterior limit 

 of tlie bill (h.). The two halves of each portion unite with each other in the middle 

 line, in some instances becoming confluent, but in others uniting in a tendinous tract at 

 their junction. The anterior portion is never, in any way, attached to the hyoid bone, 

 and simply passes across the inter-ramal area, ventrad of the hyoid ; between its median 

 part and the body of the basihyal there lies a glandular organ of tough consistency 

 which opens to the buccal cavity by paired lateral ducts, and, in addition to any 

 glandular function which it may perform, serves to bring the muscle into mechanical 

 connection with the hyoid. The posterior portion (text-fig. 15, p. 260) is usually 

 inserted into a bony or cartilaginous nodule (N.) which articulates with the ventral 

 surface of the urohyal, and to which it is closely bound by a sheath of connective tissue ; 

 quite exceptionally it may be inserted into the basihyal just at the origin of the urohyal. 



In contrast to the condition existing (4) among the Ratites, Eaptores, and Penguins, 

 the muscle, with one exception, is confined to the anterior third and less of the inter- 

 ramal area, and in many exhibits evident signs of retrogression. In a few instances 

 the anterior and posterior parts are about equally strongly developed, but in the 

 majority the latter is less well developed than the former, and in some has almost 

 disappeared. The anterior portion in a large number of Parrots exhibits evidence that 

 it was primitively more extensive in a posterior direction. In some cases the lower 

 jaw is backwardly extended, and the two portions of the muscle are then completely 



