1893.] THE AJfATOMT OF PABROTS. 511 



anterior and miclcUe tendons are usually fused in the upper part 

 of their course. 



Another point which we noticed about the tensor patagii was 

 that in some cases it completely covered the posterior deltoid 

 muscle and in others left it more or less exposed. 



In addition to the amount of exposure of the posterior pai't of 

 the deltoid, we found that the two parts of that muscle varied in 

 their relative sizes to one another. 



The last point that we noticed in the myology of the arm was 

 the presence or absence of the lower head of the anconeus ; when 

 this was found it was attached to the shaft of the humerus either 

 in front of or very slightly above the insertion of the latissimus 

 dorsi and altogether below the tubercle for the attachment of the 

 pectoralis minor. 



The lower head of the anconeus is present in the following six 

 genera — Cacatua, Nestor, Striwjops, Pifrrlmlopsls, Ara, and Calypto- 

 rhynchus ; while in the following twenty-one it is absent^ — C'hri/sotis, 

 Deropty%is,Psittacula, Aprosmictus, Poeocephalus, Caica, Tanygnathus, 

 Eos, Eclectus, Lathamus, Paheomis, Loriculus, Psepihotus, Lorius, 

 Conurus, Coracopsis, Cyanorhamplms, Pionopsitta, BolborJiynchus, 

 Platycerms, and Psittacus. 



In all the genera in which we have found a lower head to the 

 anconeus, the posterior deltoid was only partially covered by the 

 posterior edge of the tensor patagii ; while among those in which 

 the lower head was not found, the deltoid was completely covered, 

 with the following exceptions— ^t'^ethts, Coracopisis, Pionopsitta, and 

 Bolborhynclms. In the latter, however, the muscle only just 

 appeared behind the edge of the tensor patagii. In the five genera 

 in which the lower head of the anconeus was found, the posterior 

 deltoid was larger than the anterior with the exception of Pyrrhu- 

 lopsis, in which also the lower head of the anconeus was but 

 slightly marked. 



In the genera in which no lower head was found to the anconeus 

 the rule seems to be that the anterior deltoid is larger than the 

 posterior ; the following are exceptions : — Coracopsis, in which 

 the posterior is the larger ; and Poeocejphalus, Eclectus, and Bolbo- 

 rJiynchus, in which the two deltoids are of equal size. 



The arrangement of the tendons of the tensor patagii is very 

 much the same in Nestor, Stringops, and CalyptorJiynchus ; 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 

 Calyptorhynchiis 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 genera, 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, but closely correspond to the arrangement in the birds 

 last named. 



Eos, Lwius, Pceocephalus, and Caica have a characteristic and 



