( 203 ) 



prominent, and the antero-lateral processes are relatively larger. INIoreover the keel 

 has undergone considerable reduction, its height being to the length of the sternum 

 in the middle line as 15 to 100, while in F. atra and F. cristata the proportions are 

 as 25 and 23 to 100 respectively. The inferior border of the keel is straighter, and, 

 in some specimens, it dies away somewhat farther in front of the posterior extremity 

 of the sternum than in the recent forms. The xiphoid processes are rather broader 

 and the lateral notches are frequently unsymmetrical. 



From the sternum of F. neivtoni as figured by Newton & Gadow * our 

 specimen differs in (1) its undivided prominent spina externa with a sharp 

 ventral ridge (as in F. atra) ; (2) in the greater reduction of the keel. On the 

 other hand, in the straightness of the lower edge of the keel the two resemble one 

 another. 



In the specimen figured there are five pairs of articulations for sternal ribs, but 

 in others there are six, the small additional pair being anterior to the others, on the 

 side of the antero-lateral processes. The coracoid grooves are a little more widely 

 separated from one another than in F. atra. 



In the following table the dimensions (in millimetres) of three sterna of Palaeo- 

 limnas, together with those of Fulica atra and F. cristata, are given : — - 



Specimen A is the one figured on PL X., figs. 1 and 2. It will be seen that 

 although in most of its dimensions it is the largest of the three, its keel is the least 

 developed. 



The coracoid (PL IX., figs. 9, 10) differs from that of F. atra, in possessing a 

 stouter shaft and a more prominent hyosterual process (j^^'O^^^sus lateralis) ; the 

 clavicular process also is relatively rather larger. The dimensions of the figured 

 specimen are : length, 48 mm. ; width of lower extremity, 22 mm. 



The scapula is wider in the blade than in F. atra, but is otherwise similai'. 

 The dimensions of the scapula associated with the figui'ed coracoid are : length, 

 78 mm. ; width of proximal end, 13 mm. ; width at the middle of the blade, 6 mm. 

 In a scapula of F. atra the corresponding measurements are 60, 11, and 3-5 mm. ; 

 and in one of F. cristata 64, 11, and 4. 



As far as one can judge from the disarticulated bones, the coraco-scapular 

 angle was about the same as in Fulica. 



The fwrculum is closely similar to that of F. cristata, but the arms are some- 

 what thicker in proportion to their length, a somewhat remarkable point, since 

 reduction in this part of the skeleton usually accompanies a decrease in the power 

 of flight. The extreme length of each clavicle is 49 mm. 



The humencs, and indeed the whole of the wing-bones, are considerably 



'"On Additional Bones of the Dodo and other Kxtinct Birds of Slaiu-itius," Tram. Zmtl. Soc, 

 Vol. Xlll., p. 21)2, PI. XXXV., figs. 5-7. 



