OF THE TOXGUE OF PAEROTS. 233 



hyal near the root of the nrohyal ; the accessory muscle is much more strongly 

 developed. The muscle in C. triton is like that in C. alba, but the division of the 

 accessory muscle is not so well marked and appears to be incipient rather than actual. 

 In addition, there is present on the left side a very narrow muscle that arises from the 

 extremity of the cartilaginous continuation of the urohyal and is inserted into the 

 fourth tracheal ring ; in its origin and narrowness it resembles a similar muscle in 

 Edectus (text-fig. 7, th.h.a., p. 231), but differs from it in its insertion. In C. sulphurea 

 the thyrohyoideus is divided into two, the anterior division arising from the apex 

 of the parahyal process and the posterior one from the posterior half ; both are inserted 

 into the ventro-lateral surface of the thyroid. The thyrohyoideus accessorius consists 

 of two divisions, the origins of which have been shifted forward to the cylindroidal 

 portion of the basihyal and are inserted to the posterior end of the thyroid. The 

 muscle is therefore more complex than in other species of Cacatua, and the origin of 

 the accessory muscle is much more anterior. In Caloj^sittacus novce-hollandice the 

 muscle resembles that in Cacatua alba, but the accessory muscle is divided into four 

 narrow bundles, the collective origin of which is nearly the same as that of the two 

 bundles in G. alba, but has a slightly more posterior extension, since the hindmost 

 two of the four arise from the lateral surface of the anterior end of the urohyal. 



In Edectus pedoralis (text-fig. 7, p. 231), Foeocephalus robustus ^, and Nasiterna 

 jnisio, the accessory muscle exhibits an unusual arrangement. It is very narrow, and 

 arises, not from the basihyal, but from the posterior extremity of the urohyal, and is 

 inserted at the anterior end of the thyroid. In Nasiterna it widens very much at its 

 insertion. In Stringops habroptilus (PI. XXVII. fig. 18) and Microc/lossus aterrimus 

 the accessory muscle (th.h.a.) is quite separated from the parent one, and its origin is from 

 the posterior edge of the basihyal and the outer margin of the urohyal ; its insertion 

 is partly to the posterior border of the thyroid and partly to the first tracheal ring 

 behind that. In Microglossus the thyrohyoideus extends forwards beyond its origin 

 at the parahyal process as a small muscular tract, which forms a second origin at the 

 posterior extremity of the entoglossum ; the tract on the riglit side is about three 

 times as large as that on the left. In Nestor notabilis (PI. XXVII. fig. 22) the thyro- 

 hyoideus arises from the posterior two-thirds of the parahyal arch and to a small 

 extent from the dorsal surface of the body of the hyoid ; the extension of the origin 

 backwards on to the basihyal is suggestive of one of a primitively more extensive nature. 

 The thyrohyoideus accessorius is like that in 8trmgops and Microglossus, except that 

 at its origin the muscle is narrowed. There is also present a muscle which I have not 

 found in any other Parrot : it arises from the sheath investing the urohyal, turns out- 

 ward and runs over the surface of the ceratohyoideus, round the lateral ceratoglossal 

 to the dorsal surface of the tongue, thence over the sternohyoideus and thyroglossus 



' But not in P. rii 



