86 • NEW YORK STATE MUSEUM 



together, and by their more ventral disposition they have become 

 pecuharly conspicuous. 



The bending downward and forward of the i)ostacetabular 

 region of the pelvis is not as well marked in Ictinia as it is in 

 Circus, nor are the gluteal ridges nearly so prominent and sharp 

 in the first as they are in the last mentioned genus. 



There are no marked differences in the skeletal composition of 

 the pectoral limbs of Ictinia and Circus; while upon comparing the 

 pelvic limbs of these two genera, we find in addition to a simple 

 proportionate discrepancy in the relative lengths of the long bones, 

 the fibula is comparatively longer in Ictinia (reaching almost to the 

 condyle) ; the procnemial crest of the tibiotarsus is not so evident; 

 nor is the outer one of the two processes composing the hypotarsus 

 of the tarsometatarsus. In Ictinia the basal joint of the second toe 

 fuses with the joint next beyond it. 



Our next form for comparison is the lovely Swallow-tailed kite, 

 Elanoides forficatus, of which I have at the present writ- 

 ing two skeletons, and several parts of skeletons. In its osteology 

 it offers a number of points of difference with Ictinia missis- 

 s i p p i e n s i s , and also with Circus. Nevertheless, in its 

 general contour the skull of this kite more nearly resembles the 

 skull of Circus then it does the skull of Ictinia, nor is this a. mere 

 resemblance, for in some particulars they are actually more alike. 



As compared with Circus then, we find the superior osseous 

 mandible not so deep in the vertical direction through its base ; the 

 anterior portion is quite as decidedly hooked but more slender, and 

 the narial apertures are rounder. The lacrymals are a good deal 

 alike in the two forms, but in all of the six skulls of Elanoides at 

 my command none show an " accessory piece " to this bone, and 

 the superior portion is much reduced. It may, however, be found 

 to be present in the future. Possibly, however, the accessory piece 

 may be present in other specimens, but if so, I am sure they will 

 be found to be very small. Skulls of Elanoides differ among them- 

 selves in the width of the frontal region between the orbits su- 

 periorly, but they always have a far more decided width here than 

 any skull of Circus. Each has a supraoccipital prominence, but in 

 the kite, a well marked pit or dimple is to be observed upon either 

 side of it. The pars plana is slenderer and its lower wing more 

 projecting in Elanoides, and the deficiency in the interorbital septum 

 rather small, otherwise the parts nearly agree. The nasal septum 

 is more complete than it is in Circus, being filled in by bone supero- 



