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Show 1889.] MR. "W. K. PARKER ON STEATORNIS CARIPENSIS. 173 articulate with it, and the distal free end is narrow, terete; it ossified, proximally, by a separate centre. The posterior cornua are 31 millim. long; they are feeble, rather straight, and the upper piece, which is 11 millim. long, has its distal half cartilaginous. III. The Vertebral Chain and Ribs. The vertebral formula of this bird is as follows : - C . 15, with 3 pairs of ribs, free, on the left, and 4 on the right side ; D. 4 ; S. 13, the first with large free ribs, this and the next two, with arrested ribs, buttress the pre-ilia; the 13th vertebra not firmly ankylosed to the 12th ; Cd. 7 + 4 or 5,= Total 43 or 44. The proccelous articular facet of the atlas (Plate XIX. fig. 1, at.) is somewhat transverse, and this cup is largely notched for the odontoid process of the axis (Plate XVIII. fig. 3) ; not perforated as in most of the high arboreal birds. The atlas has no lateral passages for the vertebral artery ; its centrum articulates with the axis by the normal flat facet. The odontoid process of the axis is large (Plate XVIII. fig. 4) ; this bone (Plate XIX. fig. 1, ax.) has thick, blunt upper and lower spines, and oblique ascending snags over the post-zygapophyses ; a pair of small upper fenestree, and, what is very rare in birds, well-formed rib-bars (cr2.) to enclose the canal for the vertebral artery ; the articulation of the centra throughout the rest of this region is cylindroidal. The 3rd cervical (Plate XIX. fig. 1) has also blunt upper and lower spines, lateral fenestrae, above, a wide top, and a definite snag over each post-zygapophysis, and a rudimentary rib, right and left, bounding the canal for the vertebral artery ; this part is 3*5 millim. long. The 4th cervical (Plate XIX. fig. 1) has its sides notched, not fenestrate; it has both upper and lower spines, somewhat larger riblets, and spines on the post-zygapophyses. The 5th cervical is much like the next four or five; but in this strong chain of bones each succeeding vertebra is larger and stronger than the one in front of it ; towards the chest they become shorter, as well as wider. This 5th bone, like the rest up to the 12th, has large riblets ; on the 5th, 6th, and 7th these styles reach back within 2 millim. of the end of the centrum. None of these vertebrae have the inferior or carotid canal developed, for the inferior face is wide open and gently concave in front; at the middle they are sub-carinate, and flat behind, where they broaden out into the apparently convex, but really concave, hinder facet. The wide canal for the vertebral artery, right and left, is only complete in the front third of each vertebra, and only on the 10th, 11th, and 12th is there any rudiment of the oblique bar (or flying buttress) so common in the Coccygomorphae, a growth that partially finishes the lateral bony wall. I have mentioned that the 3rd has large lateral holes above, and that the 4th is notched, and not fenestrate. The 5th also is notched on its outer and upper edge ; but the hinder margin of each notch is developed into an oblique, bony bar, which, running forwards, inwards, and upwards, forms by union with its fellow a |