30 
DR. W. KOWALEVSKY ON THE 
didactylity, I propose to name it Diplopus, and to add to the special form found at Hord- 
well the name of M. Aymard, who has contributed so much towards the advance of our 
knowledge of this extinct group. I will therefore describe the animal from Hordwell 
under the name of Diplopus Aymardi. 
From the point of view of pure descriptive osteology, it would be perhaps better to 
describe the Hyopotamus from Hempstead and Puy and the Diplopus from Hordwell 
separately. I have been prevented, however, by many reasons, from following this course, 
and I have preferred to give a comparative description of both genera: as the number of 
my Plates was limited, I could not figure ail the bones belonging to both ; and in 
the case of entirely similar bones, I gave preference to those which were better preserved. 
The present paper contains only the description of the long bones of the skeleton and 
of the limbs. I hope soon to be ready with the description of the vertebrae, skull, and 
dental characters. My best thanks are due to the officers connected with the Osteo- 
logical and Geological Departments of the British Museum, as every thing which could 
in any way favour my studies was accorded in the most liberal way. My special grati- 
tude is due to Mr. William Davies, of the Geological Department, to whose kindness 
and the interest he has taken in my work I owe very much. I am indebted to him for 
many valuable suggestions, and for the unremitting kindness with which he assisted me 
in looking over and over again through the rich stores of fossil remains contained in 
the galleries of the National Collection, and for aiding me in my comparisons in every 
possible way. 
The Bones of the Skeleton. 
The Scapula (Plate XXXV. fig. 1, •§- nat. size). — This is a bone that has generally the 
least chance of being preserved fossil, owing to its flat shape and consequent thinness. 
Happily, however, thanks to the excellent method by which the bones from Hordwell were 
collected by Mr. Keeping, we have now in the British Museum, besides several detached 
fragments, a complete right scapula* from Hordwell, which belonged to the didactyle 
animal named by me Diplopus Aymardi. The chief characteristic of this fossil scapula is 
its enormous breadth compared with the antero-posterior length. No living Ungulate 
shows us such a broad scapula, the nearest approach to it being made perhaps by the 
scapula of Hippopotamus. Among the fossil Ungulata, the Anoplotherium (Blainville, 
Ost. Anopl. pi. iii.) comes even nearer to it, by the broad expanse of the horizontal 
part and by the large acromial process ; there is, however, a marked difference between 
the two in the shape of the glenoid cavity, which is very oval in Anoplotherium and 
nearly circular in Diplopus. The coracoid process is not very prominent, but larger 
than in the recent Suinse ; it is separated from the glenoidal fossa by a slight notch, 
retreats a little backwards, and does not reach the level of the inner margin of the 
fossa. The fossa glenoidea is moderately deep, with a sharp margin raised all round. 
The spine of the scapula is very high and sharp, set very obliquely on the horizontal 
* As many bones -were drawn without mirror (not reversed), it may happen that some of them described as 
right may be really left in the original. I shall, however, adapt my descriptions to the Plates, and describe the 
bones as they appear in the drawing. 
