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Show 1889.] MR. W. K. PARKER ON STEATORNIS CARIPENSIS. 181 (Caprimulgus and Chordeiles), there is a rudiment in Steatornis, in Cuculus canorus, and in Buceros ruficollis; this part is nearly as large in Geococcyx affinis as in Aptergx. In Ceryle alcyon the post-ilium sends backwards a process (its proper termination) over the ischium, which only measures 15 millim.; this spur is very long in Steatornis; it is 10 millim. in length; the ischium and pubis both project far backwards also as long ligulate processes, cartilaginous for their greater part. The pre-ilium (pr.i.) in Steatornis sends forwards a spike in front of the ear-shaped fore lobe of the bone; this is formed by the junction of the inner edge of the bone with the diapophysis of the underlying vertebra-the 1 st' sacral. The " sacro-ischiadic " fenestra (s.i.fi) is oval; it is 8 millim. long by 4 millim. wide ; its broad end is in front. The bony junction of the post-ilium (pt.i.) and ischium, behind this fenestra, is 1*5 millim. in extent. The ischium (isc.) runs back quite free from the pubis (pb.) ; it keeps at a distance from it; its whole length is 38 millim., and its free projection, next below that of the post-ilium, is 13 millim. long; it is 6 millim. wide in front of the fore part. The pubis is only 2 millim. wide in front and 3 millim. behind; its whole length is 47 millim., and the chord of the arc formed by this rib-like bone behind and the pre-ilium in front is 74 millim. This is a peculiar form of pelvis, so broad, gently convex, and free from all strong outgrowths; it is only in birds whose hind limbs are small and feeble, such as Cypselidae, Trochilidae, Alcedinidae, and the like, that such a pelvis is possible. Even among the Cuculines, whenever the legs are strong, we get a great contrast to this, e.g. the Musiphagidae, and such Cuculidse as Saurothera and Geococcyx. The Hind Limbs (Plate XIX. figs. 4, 5) of Steatornis are, as I have said, only half as large as the wings; I here compare them, in the measurement of the main regions, with those of the Kingfisher and Goatsucker:- Femur. millim. Ceryle alcyon 29 Caprimulgus europceus 21*5 Steatornis caripensis.. 38 Here we see that, roughly speaking, the femur (/.) is three fourths the length of the tibia (t.) in Ceryle and Steatornis, and a little more than two thirds in Caprimulgus. The tarso-metatarsus (t.mt.) is little more than half the length of the 3rd digit in Ceryle, more than two thirds in Caprimulgus, and considerably less than half in Steatornis. The relative size of the bones of the leg and foot, on the whole, in the last of these birds is very similar to what we find in the Cyp-selidee, Caprimulgidae, and Alcedinidae; for in all these families the hind limb is very feebly developed. This is very marked also in PROC. ZOOE. Soc-1889, No. XIII. 13 Tibia. ff°" j.r* • metatarsus, digit. millim. millim. millim. 39 12*5 24 29 14 20 48 17*5 37 |
