230 jMH. G. r. MUDGE OS TDK MYOLOGY 



viridirieno tlicre is a rudimentary bifid tendon a little smaller than that iu Coiiunrs 

 jemlaya (PI. XXVI. %. 9), hut otherwise similar. In Chrysotis jianamennis (1*1. XXVII. 

 fig. 11) tlu-re is an unpaired ceratoglossus superior accessorius {cy.s.a.) arising from 

 the left-hand p.iront muscle and attaclied to the root of the urohyal. In Chrijsofis 

 wstiva the attachiiunit of the muscle to the fascia of the mesoglossus is unique ; a small 

 triangular cartilage, having rounded ventral and dorsal surfaces, is fixed by its base to 

 the mesoo-lossus, while its other two sides form an insertion for the two halves of the 

 superior ceratoglossus, each to each. The position of this cartilage with respect to 

 the hyoid bone is immediately dorsad of the slight concavity in the rounded extremity 

 of the basihyal. Apparently this concavity is present in the hyoid bones of all 

 Parrots so far examined {cf. Mivart, P. Z. S. 1895 and 1896), but no meaning can be 

 attached to its presence. So far as this Parrot is concerned, this little cartilage 

 explains the concavity, for together they form a shallow ball-and-socket joint 

 arrangement. The cartilage is present in no other Parrot, while the concavity is 

 almost generally so. There is also present a bifid tendon, similar in its relation and 

 strength of development to that in Conurus jendaya (PI. XXVI. fig. 9). In Nasiterna 

 pusio the muscle is like that in Chri/sotis ochrocephala, but does not possess the lateral 

 bundle of fibres on either side. 



In Pyrrhilopsis s})lendens and P. fersonata the muscle is like that in Omjsoth 

 oclirocephalus, but the muscle is splitting posteriorly into a larger dorsal and a smaller 

 ventral bundle ; the former arises from the hypobranchial, and the latter from the 

 basihyal. 



In Psitiacns erithacus (PL XXVII. fig. 15) the muscle extends back along the 

 anterior half of the hypobranchial, but at that point where is its insertion in other 

 Parrots it is continuous with the mesoglossus muscle, and is not inserted into the 

 fascia of that, as in other Parrots. 



In Conurvs jendaya (PI. XXVI. fig. 9) the muscle arises, as in Stnnyops, from the. 

 anterior third only of the hypobranchial, and it possesses a bifid tendon of insertion, the 

 rami of which extend along the middle of each muscle, and not along the inner side 

 as in Stringops and Psittitms. There is present on the right side only a ceratoglossus 

 superior accessorius [cg.s.a.) — a unilateral condition similar to that in Chrysofis 

 panamensis, but occurring on the opposite side of the tongue. In C. cactorum it is 

 like that in C. jendaya, but there is no accessory muscle. In C. holochlorus as in 

 C. cactorum, but the bifid tendon is more strongly developed than iu any other species 

 of Conurus. In Cyanolyseus jyatagonicus and Loriculus galgulus as in C. cactorum, but 

 there is no bifid tendon. In Pinopsittacus pileatus as in Conurus cactorum. 



In Eclectus pectoralis (text-fig. 7) the origin of the muscle is from the anterior 

 fifth only of the hypobranchial, and the bifid tendon of insertion is very broad, its 

 rami extending backwards over the dorsal surface, in the mid-line of each half of the 

 muscle. 



