170 SHOULDER-GIRDLE AND BREAST-BONE. 



Shoulder- and Breast-bones of Agapornis pullaria (one and a half diameter). The scapula (sc.) 

 is ensiform, gently curved, enlarged at its upper third, and then very pointed. The acromion is 

 short and square ; it articulates with the upper part of the meso-scapular segment inside the head 

 of the coracoid. This latter bone (cr.) is an elegant, long, phalangiform ray ; it has the head 

 enlarged, the meso-coracoid process well developed, and the epicoracoid spur moderate. The 

 meso-scapular segment (m. sc. s.) is here a separate, hatchet-shaped bone, with, no clavicle 

 attached ; it lies on the inside of the head of the coracoid, and the meso-scapular spur and the 

 meso-coracoid spur curl round to articulate with it. This bone is a rudiment of the compound 

 "furcula;" but it is not part of the clavicle, which here, as in Mclopsittacus undulatus, 

 Psephotis multicolor, &c., is entirely absent. In Psephotis multicolor the meso-scapular segment 

 coalesces with the head of the coracoid. In the larger (and in some small) kinds of Parrots, 

 for instance, Manodes discolor, the " furcula" is developed (see Plate XIV, figs. 16, 17, which 

 shows that of PsMacus erythacus), the clavicles becoming anchylosed to the meso-scapular 

 segment in old age, but having no inter-clavicle at the angle. The furcula is V-shaped, and its 

 rami are flat and rather feeble. I have already spoken of the furcula of the Psittacime 1 (see 

 'Proc. Zool. Soc.' (1865, p. 238) in a description of the osteology of Microglossa alecto. The 

 Sternum, of the Parrot-tribe is very characteristic, yet it is but slightly modified from that which 

 is seen in many of the Picarise, the more typical forms all possessing a Breast-bone very different 

 from that of the Passerinse. The general outline is oblong, the length being more than twice the 

 breadth ; the upper surface is deep, especially in front ; the more shallow, hinder part is expanded 

 (see Plate XIV, fig. 15) and rounded. As a rule, there is only one fenestra a notch in some 

 cases on each side. This is very apt to fill in, especially on one side. There are six pairs 

 of condyles for sternal ribs, surmounted in part by a somewhat hooked costal process. This 

 is not curved backwards in Agapornis (see Plate XIV, fig. 15). The coracoid grooves are 

 quite distinct, but the space between them is small ; above this space the upper lip is often 

 slightly notched ; below, the " rostrum" (r.) stands like the figure-head of a ship ; it is thick, 

 grooved in front, slightly notched above ; and below only a shallow scooping separates it from 

 the front of the keel. This latter part often projects in front of the rostrum below, and this 

 front margin forms a right angle with the base of the body of the Sternum ; altogether, the keel 

 is very large in proportion to the wing-bones, and it runs to the end of the Sternum (see 

 Plate XIV, fig. 15). In the Owl-billed Parrot of New Zealand (Strigops habroptilus, Plate XVII, 

 fig. 15) the Sternum is very aberrant; the coracoid grooves are small and wide apart; are 

 separated by a shallow notch ; and the keel is very small both short and low. The body of 

 the Sternum is very shallow ; a small double " fenestra" is seen on the left side, and two on the 

 right side ; this is quite aberrant for a Parrot. The middle xiphoid region is produced 

 backwards ; this also is abnormal. In some of the medium-sized Red-and-Green Parrots the 

 middle xiphoid is notched at the mid-line. 



1 That little paper was written before I had thoroughly mastered the development of the Shoulder- 

 and Breast-bones. I was wrong in saying (p. 238) that the " ento-sterual structures really belong 

 to the shoulder- girdle," they are merely correlated , and belong to the costal arches. Also, I con- 

 fused together the " meso-scapular," and the prse-coracoid segments of cartilage ; moreover, I have 

 since discovered that the "acromial'-' (meso-scapular) bone does exist in Psephotis; but that it coalesces 

 with the coracoid. 



