OCR Text |
Show 1893.] THE ANATOMY OF PARROTS. 511 anterior and middle 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 aud in others left it more or less exposed. In addition to the amount of exposure of the posterior part 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 tbe attachment of the pectoralis minor. The lower head of the anconeus is present in the following six genera-Cacatua, Nestor, Stringops, Pyrrhulopsis, Ara, and Calypto-rhynchus; while in the following twenty-one it is absent-Chrysotis, Deroptyus, Psittacula, Aprosmictus, Poeocephalus, Caica, Tanygnathus, Eos, Eclectus, Lathamus, Palceornis, Loriculus, Psephotus, Lorius, Conurus, Goracopsis, Cyanorhamphus, Pionopsitta, Bolborhynchus, Platycercus, and Psittacus. In all the genera in which w~e 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-Eclectus, Coracopsis, Pionopsitta, and Bolborhynchus. 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 Pyrrhulopsis, 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:-Goracopsis, in which the posterior is the larger; and Poeocephalus, Eclectus, and Bolborhynchus, 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 Calyptorhynchus; 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 partof 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, Lorius, Poeocephalus, and Caica have a characteristic and |