162 DR. J. MURIE ON GEOPSITTACUS OCCIDENTALIS. [Feb. 27, 



and the digits are concerned. The first form is no doubt the stouter- 

 limbed of the two. Platycercus approaches nearer to them than does 

 Euphema. 



The same remarks apply to the claws. Curiously enough, the 

 claw of the fourth digit in Geopsittaciis slightly surpasses in length 

 that of Pezoporus, although the remaining claws are the shortest. 



While discussing the external characters, I shall just add a few 

 remarks bearing somewhat upon the physical contour of Geopsitta- 

 cus. 



I had the opportunity of comparing the body of this bird, when 

 disrobed of skin and feathering, side by side with those of Platy- 

 cercus Jlaveolus, Lorius chlorocercus, and Calopsitta novce-hollandiw 

 in a similar condition. It then appeared that Geopsittaciis and Pla- 

 tycercus were nearly alike with regard to their muscular develop- 

 ment and proportions of depth to length of body and keel. The 

 former, however, had very slightly the advantage over the latter in 

 vertical depth posteriorly. Lorius chlorocercus, with a much longer 

 body than any one of the other species, had less vertical depth ante- 

 riorly than Platycercus and Geopsittacus, and only slightly more 

 than Calopsitta. On the other hand, while the three last-mentioned 

 genera more nearly agreed in the depth of the body behind, Lorius 

 differed from them all in its being much greater. 



These limited observations would seem to indicate that the chest 

 or wing-giving power is greatest and nearly alike in Geopsittacus 

 and Platycercus, whereas Lorius and Calopsitta are stronger rela- 

 tively towards the rump and in the abdominal region generally. 

 Expressed in antithesis it points to volatorial powers versus scan- 

 sorial habits. 



Circumstances, I regret, onl}'^ permitted me to examine the osteo- 

 logy through the sternum, which possesses characters in common 

 with those of the Parrot tribe. Its body is elongated in shape 

 (1""7), narrowest (0"'65) and deepest forwards, shallowest and 

 expanded (0"'8.t) behind. The middle xiphoid region * shows a 

 tendency to be produced ; but this is so slight as barely to break the 

 regularity of the arch of the posterior border. There is a large 

 fenestra on each side, of an oval figure. These, in the specimen 

 in question, have an irregular margin, from partial filling-in of deli- 

 cate osseous material. At an earlier stage, therefore, the fenestrte 

 must have been proportionally larger and more ellipsoid in contour. 

 The keel is large and deep (0"'6 anteriorly) and has a gentle but 

 not greatly projecting anterior curvature, fashioned after the manner 

 of the prow of a steam -ram. 



There are six pointed serrations, or costo-condyles, for the attach- 

 ment of as many sternal ribs. 



* In the description of the sternal bones, I have throughout followed the 

 terms adopted by Mr. Parker in his recent " Monograph on the Structiu-e and 

 Development of the Shoulder-girdle and Sternum in the Vertebrata," Ray Soc. 

 1868. The breadth of his researohes and tlie sequence in the developmental con- 

 dition of the parts examined by him give us a more trustworthy basis than 

 heretofore. 



