522 



D]l. C. W. ANDREWS ON A 



lower end of the furcnlnm. This surface looks nearly directly 

 foi'wards and is concave from above downwards ; seen from the 

 front (text-fig. 2) it is somewhat constricted in the middle, the 

 constriction apparently separating distinct upper and lower arti- 

 cular facets, between which there is a roughened area ; the upper 

 facet is the more clearly defined, and the whole structure indicates 

 the existence of an extremely strong union between the stei-num 

 and the lower end of a very large furcula. The ventral border of 

 the keel is gently convex from before backwards, and also from 

 side to side, the middle line being marked by a longitudinal inter- 

 inuscular ridge. It is about 2"6 cm. wide in front, but narrows 

 rapidly to about l"5cm.; furthei- back the width becomes still 

 further reduced. 



Text-fiffure 3. 



Sfi.ext. 



Sternum of Gigmitornis eaglesomei, from side. \ natural size. 



e.g., coracoid groove ; f., facet for furcula ; m.r., intermuscular ridge ; 

 sp.ext., spina externa. 



The lateral surface of the keel is slightly concave both from 

 above downwards and before backwards ; the concavity is most 

 marked beneath the hinder end of the coracoid grooves, where the 

 bone is very thin. The intermuscular ridge between the surfaces 

 for the attachment of the pectoralis inajor and pectoralis secundus 

 is extremely sti'ongly developed. It commences about 2 cm. 

 behind the middle of the clavicular facet, and for a short distance 



