318 EB. Thurlow Leeds—On Metriorhynchus. 
of the scapula and coracoid. The posterior facet is smooth and some- 
what irregular in shape; this facet, together with the rounded, slightly 
concave facet on the coracoid, forms the glenoid cavity. 
The distal extremity differs from the extremities of the metatarsals, 
with which the scapula has been confounded, by the absence of a 
marked ridge, which always bounds their articulating facets. Im the 
scapula the end of the bone is merely the oral shaft flattened out and 
rounded off. 
Fore-limb.—The fore-limb was small, consisting of the humerus, 
radius and ulna, and some more small bones, of which the bone 
figured by Dr. von Arthaber' in pl. xxv, fig. 2, is probably one, 
though he has undoubtedly represented it wpside down. The limb was 
not a leg for walking, similar to the hind one, but either a degenerate 
paddle or an incipient one, as Professor E. Fraas* declares it to be in 
the case of Geosaurus, in his interesting work on the marine crocodiles 
(Thalattosuchia) of the Upper Jura. 
Dr. von Arthaber’s restoration of the fore-limb is certainly erroneous ; 
for in order to construct it he has had to borrow from other parts of 
the body, viz. the scapula-—which he denies to be such—and the first 
metatarsal, to form the radius and ulna. The whole leg, as he 
represents it, is entirely out of proportion to the size of the humerus, 
which would be incapable of carrying such a limb, and further in no 
way resembles the fore-limb of Geosauwrus, which he takes as a model 
on which to complete the parts of Metriorhynchus unknown to him. 
All Dr. von Arthaber’s remarks must be received with extreme 
caution, not only on account of the undoubted incorrectness of some of 
his statements, but also because of the absence of careful observation 
and editing which his work shows. For example, apart from the 
errors in regard to the pectoral girdle and fore-limb, which I have 
already pointed out, in pl. xxiii, fig. 8, he figures a left side rib 
as one belonging to the right side, and in pl. xxv he calls the pubis 
the ischium and vice versd, while in pl. xxvi he has them correctly 
named. 
I think it will be of interest in connection with this paper to 
give a short account of the method of occurrence of the bones 
found in the Oxford Clay of the Peterborough district. A remark of 
Dr. von Arthaber’s* leads me to suppose that he thinks the specimens 
of Metriorhynchus are found in such quantities as to make it hard to 
distinguish one from another, but this is not the case. The area in 
which they are found consists of brickyards, extending nearly two miles 
along the Great Northern Railway from Peterborough to London, and. 
the clay is worked to a depth of 35 feet or more. JMetriorhynchus, 
like the other animals occurring in this clay, is found at all depths, - 
and at considerable intervals of time in the various pits. Bones that 
are termed ‘associated sets’ are found at the same time, and at the 
same level, in close proximity, if not in position as the carcase of the 
animal was buried. If there were any doubt as to their belonging to 
1 Beitrége z. P. und G. Osterreich Ungarns, 1906. 
2 “Die Meer Crocodilier (Thalattosuchia) des oberen Jura’? Palaont., vol. xlix 
(1902-3). y 
3 Beitrage z. P. und G. Osterreich-Ungarns, 1906, p. 302. 
