18S9.] MR. W, K. PARKER ON STEATORNIS CARIPENSIS. 181 



{Caprimulgus and ChordeiJes), there is a rudiment in Steatornis, in 

 Guculus canorus, and in Buceros ruficollis ; this part is nearly as 

 large in Geococcyx affinis as in Apteryx. 



In Ceryle alcyon the post-iHum 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 1st sacral. 



The " sacro-ischiadic " fenestra (s.i.f.) is oval; it is 8 millim. 

 long by 4 millim. wide ; its broad end is in front. The bony junc- 

 tion of the post-ilium (jpt.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 milhm., 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 4/ 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, Trochilidse, 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 Musiphagidfe, and such Cuculida? as Saxirothera 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 reliitive 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- 

 selidae, Caprimulgidse, and Alcedinidse ; for in all these families the 

 hind limb is very feebly developed. This is very marked also in 



Proc. Zool. Soc— 1889, No. XIII. 13 



