232 1^1 1:. fi. r. ilUDGE ON THE MrOLOGY 



In Lorhis domicella (Tl XXVII. fig. 21) the muscle attains its highest develop- 

 ment, its origin extending along the whole length of the hypobianchial and at the 

 l)osterior extremity of which it is slightly tendinous. Along the posterior two-thirds 

 of its hypobranchial connection it is fused with the dorsal surface of the ceratoglossus 

 inferior posticus, lu tlic basihyal region it splits into a smaller ventral layer {cg.sa.), 

 and a larger dorsal one(c-f/.s.), of which the former has its origin from the basihyal and 

 the latter from the hypobranchial. The condition of the divided muscle is foreshadowed 

 in Fijrrliulojisis (cf. ante, p. 230). Anteriorly the two pairs of muscles become 

 confluent and merge with an elongated markedly cylindrical tendon {ten.) that inserts 

 them to the mesoglossus ; the tendon lies immediately ventrad of the symphysis of 

 the parah\al arch. In Vini australis the muscle is similar to that in Lorius domicella, 

 but the ceratoglossus snbsupcrior (rr/.ss.) is more strongly developed and extends back 

 as far as the base of the urohyal ; the muscle is merged with the ceratoglossus inferior 

 posticus at its posterior extremity only. In Lorius flavo-palliatus and Eos riciniafa 

 there is no splitting of the muscle ; in other respects it is similar lo that of 

 L. domicella. 



In Nestor notahilis (PI. XXVII. fig. 22) the muscle arises from the anterior third 

 of the hypobranchial and the two halves I'emain distinct throughout; their tendon is 

 flat and elongated and extends forward to the anterior extremity of the tongue, where 

 it becomes connected with the tendons of the hypoglossus rectus and with the covering 

 membrane of the tongue. This elongated tendon probably represents in part the fascia 

 of the mesoglossus; for in Nestor the mesoglossus muscle itself has disappeared. 



Thtrohyoideus and Thtrohyoideus accessorius Muscles. 



The thyrohyoideus, apart from its connection with the thyroglossus, exhibits very 

 constant characters in all the Parrots examined. In the majority of them it arises 

 from the anterior portion of the parahyal process and is inserted into the ventro- 

 lateral surface of the thyroid. In some it gives off upon its inner side a small 

 muscular branch, but as this is a rudiment of the thyroglossus, variations of this sort 

 will be considered under that muscle. 



In Cacatua roseicapilla and C. galerita (PL XXVII. fig. IS, th.h.) the muscle exhibits 

 the most primitive condition, and there is given off from the ventral edge of the thyro- 

 hyoideus a relatively large branch [th.h.a.)yv\i\cYi is attached to the basihyal at the base 

 of the urohyal; in other Parrots this becomes more or less separated from the parent 

 muscle, and I proi)ose to speak of it as the thyrohi/oideiis accessorius. It is slightly 

 smaller in C. roseicainlla than in C. galerita. In C. leadheateri the accessory muscle 

 is smaller, but it is partially divided into two anteriorly, and the posterior of the two 

 branches thus formed has shifted its origin to the head of the hypobranchial. In 

 C. alba, Cali/2)torhT/'jicIiusfitnerevs, and Calyptorhynclius laidsi the muscle is like that 

 in C. Icadleatiri, but the posterior branch of the accessory muscle arises from the basi- 



