or THE TONGUE OF PARROTS, 259 



arch and the dorsal surface of the body of the basihyal ; in Eos its insertion is limited 

 to the basihyal, and in Vini to the posterior half of the parahyal arch. In Nestor it is 

 inserted to the parahyal arch just behind the hypocleidium, and is thus more anterior 

 than in the Lories. 



In Ara macao (PL XXVII. fig. 20, s.h.) the muscle just before reaching its insertion 

 divides into a larger and a smaller branch, of which the former becomes inserted into 

 the parahyal process and the latter, in common with the hypoglossus obliquus and 

 thyroglossus, into the posterior extremity of the os entoglossum. In Calyptorhynchus 

 funereus the muscle just at its insertion becomes confluent with the thyroglossus. In 

 Pezoporus (PI. XXVI. fig. 8, s.h.) the muscle narrows and becomes inserted by a small 

 tendon. In Prioniturus (text-fig. 16) the muscle divides into two branches, the anterior 

 of which becomes confluent with the stylohyoideus and is inserted with it in a common 

 and tendinous insertion near the apex of the parahyal process, while the latter becomes 

 inserted by a tendinous insertion to the root of that. 



In Brotocjerys the muscle has retrogressed at the point where it turns round the 

 ceratoglossus lateralis, only the fascia persisting. 



In Ara ararauna (text-fig. 15), Flatycercits, Loriculus, Calopsittacus, and Cacatua 

 galerita the origin of the muscle at the carini sterni has undergone complete retro- 

 gression, and in the first- and last-named Parrot it is represented by a narrow tract of 

 fat. In Bolborliynchus, Psittacula, JS^asiterna, and Tanygnathus the origin is repre- 

 sented by a mere trace of muscular tissue; while in Conurus holochlorus, Eclectus, 

 Chrysotis wstiva, C. viridigena, C. ochrocephala, Poeocephalus, and Conurus jendaya it is 

 somewhat stouter, but still very narrow. In Palceornis and the remaining Parrots 

 it is well defined ; and in Nestor it is very strongly developed. In Sfringoj^s, in 

 correlation with the absence of a carini sterni, the muscle arises from the skin of the 

 thorax in this region by three strands which soon unite to form a single trunk. 



In Eos, Ptistes, Ajyrosmictus, Pezoporus, Psittacus, and Stringops the muscle is 

 continuous from its origin to insertion. In Stringops it remains free of the skin 

 throughout its course, but in all other Parrots it is attached to that along the greater 

 portion of its course. In the six Parrots just mentioned it widens and thins in its 

 mid-cervical region, except in Eos, in which it thickens as well as widens. In Lorius 

 domicella, L. flavo-])alliatus, Chrysotis ochrocephala, and Nestor it becomes exceedingly 

 attenuated in the mid-cervical region. In all the remaining Parrots the muscle has 

 undergone retrogression in this region, usually disappearing about half an inch to an 

 inch from its origin, and reappearing a little posterior to the hinder edge of the 

 serpihyoideus. 



Primitively, the muscle thus appears to have been a continuous one from its origin 

 to insertion, but it has undergone more or less extensive retrogression, principally in 

 the mid-cer^dcal region, but also at its origin and insertion. Its insertion appears to 

 VOL. svi. — PART V. No. 7. — October, 1902. 2p 



