E. Thurlow Leeds— On Metriorhynchus. 317 
Coracoid of Metriorhynchus superciliosus (Desl.). Oxford Clay: Fletton, near 
Peterborough. From the Leeds Collection, Eyebury, near Peterborough. 
That these two bones are really coracoids is proved by the fact that. 
Mr. Leeds has never found four bones of this type with one skeleton 
of Metriorhynchus, although he has several times found the entire. 
pectoral girdle. Further, an examination of associated sets of bones 
of DMetriorhynchus at EKyebury and in the Natural History Museum, 
London, shows that in some cases the coracoid has the foramen and 
in others the notch, whereas the scapula proper is the same in all 
eases. Nor can a difference of species be proposed as a solution of this. 
dissimilarity, as these two variants of the coracoid are both found with. 
the common form of WMetriorhynchus, viz. I. superciliosus. Con- 
sequently the dissimilarity can only be accounted for by a difference 
in the degree of ossification, or may be ascribed to chance or to sex. 
The mistake which Hulke made has unfortunately been perpetuated 
in Dr. yon Arthaber’s monograph,’ and it seems only right that the 
proofs given above of this grave error should be published. 
Dr. von Arthaber does not stop at this point, but proceeds to include 
the true scapula in a hypothetical and impossible fore-limb of the 
animal, a mistake which he could not have made had he compared the 
scapula at all carefully with the metacarpals and phalanges of the hind- 
limb, or with the scapula of modern Crocodilia. 
It may not be out of place here to give a detailed description of the 
scapula of I. superciliosus. 
Scapula.—lt is an irregularly-shaped, long, and slender bone, the 
anterior border being longer than the posterior; the proximal end is 
triangularly rounded, with a flattened inner surface; the shaft is 
slender and oval in section. The proximal extremity presents two. 
facets, the anterior one being rugose and triangular, corresponding to 
a similar facet on the coracoid. ‘These two facets form the articulation 
1 Beitriige z. P. und G. Osterreich-Ungarns, 1906, p. 309 ff. 
