186 Annals of the Carnegie Museum. 



very materially by gradual pressure, differently applied ; then, why 

 not, we ask, during the lapse of time, may not this result have been 

 brought about in this way? It is hard to say, for even if it has been, 

 then what are we to say about its being absent in some of the Rallidx, 

 and present again in such forms as Polyborus cheriway and several 

 other Accipitres? I rarely see in any of the old-fashioned engrav- 

 ings, representing with the appropriate surroundings below, the noble 

 falcon striking his prey, the doomed Heron, in mid-air, that this 

 peculiar and unique condition of the coracoids, present in both the 

 Hawk and his quarry, does not come into my mind. Both are des- 

 mognathous birds, yet it would hardly seem possible related through 

 any such character as this, arisen however it may. Still we are begin- 

 ning to catch glimpses of the affinities of the Herodiones, and mor- 

 phology has much yet to bring to light in the premises. Fig. 9 shows 

 these decussations of the coracoids very well, and the difference in 

 width of the hinder and anterior parts of the bone, is well shown by 

 the relative positions of the xiphoidal and costal processes ; the thick- 

 ness of the front part of the carina now becomes evident, seen from 

 this point of view. 



The coracoids and scapulre which I have taken the opportunity to 

 show above will be treated of under the head of the pectoral arch. At 

 the lower and inner angles of the coracoids, the dotted line indicates 

 the amount of decussation of these bones when in situ in their grooves 

 on the sternum. In ^. candidissima the sternum differs from that bone 

 in Ardea herodias, as I have described it above, in only the most insig- 

 nificant minor details ; indeed, in all essential particulars, it is the 

 veriest miniature of the latter bone. 



With Nycficorax, although the principal features of a Heron's ster- 

 num are still there, yet a comparison of Figs. 8 and 32 will show that 

 the bone has departed somewhat from the type form as seen in Ardea. 

 The keel is comparatively much deeper in front and slopes up far 

 more rapidly behind ; the manubrium bears a laterally compressed 

 plate on its anterior extremity, which is as long as the part which cor- 

 responds to the triangular portion in Ardea. 



Finally, the main pneumatic foramen, over the keel anteriorly, is 

 very much larger. This may contract more, however, in specimens 

 other than the one I have in hand, and in any event is a character of 

 very trivial importance. 



Of the Pectoral Arch. — Comparatively speaking the coracoid of 



