PSITTACI 259 



a primitive passerine tensor patagii brevis, to which has 

 been subsequently added an extension of the deltoid. . * 



With the general structure that has been described the 

 parrots show much difference in the details of the patagial 

 tendons. 



The arrangement of the tendons of the tensor patagii is 

 very much the same in Nestor, Stringops, and Calypto- 

 rhynchus ; in all three the tendons are relatively very long 

 when compared with the fleshy part of the muscle, and they 

 are all close to one another, so as to give the appearance in 

 Stringops of one tendon. In Calyptorhynchus the anterior 

 tendon leaves the others in the lower part of the patagium 

 and runs forwards after its usual fashion, so that the main 

 distinctive point of these three gepera, as far as the tensor 

 patagii goes, is that the middle and posterior tendons are 

 close together. In Coracopsis these tendons are separated 

 by a slight interval, bnt closely correspond to the arrange- 

 ment in the birds last named. 



JEos, Lorius, Poeocephalus, and Caica have a character- 

 istic and almost uniform arrangement of the patagial tendons. 

 In them the three tendons are very difficult to distinguish, 

 because the fibrous membrane between them, of which they 

 are only speciaUsed parts, is as thick as they are. The result 

 is that in these birds the patagial muscle seems to be inserted 

 by a broad, short, membranous-looking tendon. 



Gonurus shows a transitional stage between these last 

 genera and the typical arrangement ; the three tendons are 

 more distinct, and they are equally short and show the same 

 mode of attachment to the fleshy part of the muscle. 



Lathamus is remarkable for having the anterior tendon 

 separate in its whole length from the middle one, instead of 

 being fused with it in the upper part of its course. 



Chrysotis and Bolborhynchus have a small extra tendon 

 between the middle and posterior ones ; in C. Guildingi this 

 was only present on one side, but in G. leucocephala it was 

 found on both. 



Psittacus has three tendons which are completely separate 

 in the whole of their course, and in this respect it corre- 



