OCR Text |
Show 1885.] TROCHILID.E, CAPRIMULGID.E, AND CVPSELTD.E. 905 against the coracoids, their apices extending backwards to touch either scapula. In Nuttall's Whippoorwill an outer ledge is developed on either clavicular head to abut against the corresponding coracoid in front, a feature which is still better displayed on the part of the Cypselida (Plate L X . fig. 2, z). A scapula in the Night-hawk has the typical blade-like portion, which is more inclined to be truncated in Phalxonoptilus. Both birds have its head broad transversely, and somewhat flattened from above downwards. When articulated it rests upon rather a meagre scapular process of the coracoid, with its inner angle extended forwards to meet the clavicle, as already defined above. The elements of the pectoral arch seem to be non-pneumatic bones throughout the Gaprimulgidce. Of the remainder of the Cypseline Axial Skeleton.-We find in the cervical region of the column of Pmyptila saxatilis twelve vertebrae before meeting that one in which the pleurapophyses have become liberated as ribs. These latter are here of the most rudimentary character; for in a specimen before me, on one side the rib is merely represented by a minute rod of bone suspended from beneath the transverse process, while on the opposite side the head of the bone is found, and the whole is rather more advanced. The atlas is more than usually delicately constructed, while the axis is very narrow in the antero-posterior direction. A shallow carotid canal seems to be confined to the fourth and fifth vertebrae, the usual process taking its place after that. All these vertebrae, as a rule, are notably short, with well-developed pre-and post-zygapophyses. Beneath, the parapophyses are as long as the centra, and are placed rather close together on each vertebra. The articulations are of the heteroccelous type, and the lateral canals are very short. One very interesting feature is seen in this part of the spinal column of the White-throated Rock-Swift, and that is the ossification of the interspinous ligaments among the ultimate segments. The neural spines of the tenth, eleventh, twelfth, and thirteenth vertebrae are low and inconspicuous, and the fine thread-like ligament that joins these processes has become thoroughly ossified, the minute osseous rods thus formed articulating, at either end, with the neural spines of the vertebra in question. These vertebrae, in Panyptila, are essentially very different from the corresponding bones in Trochilus. The fourteenth vertebra possesses a pair of free ribs, which m ay or may not have uniform appendages near their lower extremities ; and this segment has likewise many of the characteristics of the dorsal series that follow. Below it develops a tricornuate hypapophysis, this process being markedly prominent on all the succeeding vertebrae, occurring also upon the first two in the sacrum, an unusual thing. The presence of this formidable series of hypapophyses is accounted for by the same law that demands their presence in Colymbus, the sole difference being that, while the latter, by the aid of his strong wings, passes |