2 



DRS. B. PETRONIEVICS AND A. S. WOODWARD ON THE 



notice, written by Dr. Woodward, who lias made use of our 

 joint observations, gives a general account of the important 

 additions to our knowledge of the pectoral and pelvic arches of 

 this primitive Jurassic bird which are now made possible. Some 

 differences of opinion between us are indicated in footnotes. 



I have to thank Dr. Woodward and also Dr. C. W. Andrews 

 for the valuable help and advice they have given to me. — B. P. 



Pectoral Arch. 



The right scapula and coracoid are completely exposed on their 

 outer face (PI. I. figs. 1, la) and apparently almost uninjured. 

 They meet in a very wide angle and are fused together, though 

 their limits are marked by a line across the glenoid cavity and a 

 not ch at its outer edge. 



The scapula (sc.), which has already been described by Owen 

 (1863) and Dames (1884), is typically avian and about twice as 

 long as the coracoid. Its distal end is slightly expanded, as in 

 Casuarius ; while its proximal end bears a well-developed acromial 

 process (a.), from which a very thin lamina of bone, with 

 roughened surface, extends to the coracoid, forming the floor of a 

 hollow (/*.) in which the furcula evidently articulated. 



The coracoid (co.) is a quadrilateral plate of bone longer than 

 wide, and not much narrowed at the upper or humeral end, 

 where it is somewhat thickened. The bone is bent at an obtuse 

 angle along a line extending obliquely from the outer end of the 

 humeral border to the inner end of the sternal border, so that the 

 infero-external half must have been almost in the same plane as 

 the expansion of the sternum, while the supero-internal half faces 

 inwards. The wide upper portion of this internal half is pierced 

 near the middle by the usual coracoid foramen. The thickened 

 upper or humeral border bears two eminences, a larger adjacent 

 to the margin of the glenoid cavity and a smaller at the outer 

 angle of the bone, where it extends a little down the outer border 

 (fig. 1 a). Below this eminence the outer border is thin and 

 slightly excavated, meeting the equally thin but straight lower 

 (or sternal) border in an obtuse angle. The inner border, which 

 meets the lower border in a right angle, appears to be still 

 thinner and forms a somewhat jagged edge in which two indents 

 are probably natural*. The upper and larger of these, which 

 is semicircular, occurs at the upper end ; the smaller indent 

 further down is bounded below by a slight prominence f . The 



* I consider that the iippe* indent is certainty natural. — B. P. 



f I think I can distinguish a faint line extending from the hollow hetween the 

 upper eminences to the middle of the lower indent of the inner horder. This may 

 perhaps mark the division hetween the precoracoid and the true coracoid — in which 

 case the glenoid eminence would be on the former, the second eminence on the latter. 

 The eminence on the coracoid would thus be homologous with the spina coracoidea 

 of the Ratites and the acrocoracoid of the Carinates, while the intervening hollow 

 would correspond with the fossa supracoracoidea of the Katites (cf. M. Furbringer, 

 ' Untersuchungen zur Morphologie und Svstematik der Vogel,' vol. i. (1888) pp. 36, 

 39., 40).— B. P. 



