Z ME, R. LYDEKKER ON DACRYTHERTUM OVINUM. 



the cranium, ifc is manifest that the latter must be regarded as the 

 actual type of the genus and species. 



In referring DicJiobune ovina to Dacrytherium I was mainly 

 guided by the character of the cranium, in which one of the most 

 striking features is the great length of the space occupied by the 

 dental series. The mandible referred to D. Cayluxi presented, 

 however, several points of difference — more especially as regards the 

 form of the canine — from that of D. ovinum, and I accordingly 

 came to the conclusion that there must be two species of the genus. 



Thus the matter stood till a few months ago, when Mr. A. Smith 

 Woodward called my attention to a series of specimens from the 

 French Phosphorites which he had brought from the Continent with 

 a view to their being subsequently purchased by the British Museum. 

 Among these specimens was a fairly well preserved cranium of 

 Dacrytherium Cayluxi, together with a nearly entire right man- 

 dibular ramus said to be associated therewith ; both having been 

 obtained from the department of the Lot. 



On comparing the cranium with the type-specimen figured by 

 Eilhol the specific identity of the two may be inferred from their 

 almost exact similarity, the last five cheek-teeth having a total length 

 of 45 millim. in both specimens. The new specimen is, however, 

 distinguished by the presence of a slight diastema between the small 

 premolariform canine and the first premolar, whereas in the type 

 all the teeth of each side are in contact. Such a variation I can 

 only regard as sexual, since we have fair evidence that more marked 

 variations of a similar nature existed in Hyopotamus. The present 

 specimen is broken off in advance of the canine, so that it does not 

 exhibit the most remarkable feature of the genus — viz. the 

 circumstance that the premolariform incisors are continued on in 

 the line of the premolars, so that the first incisors of the two sides 

 are separated from one another by an interval nearly as great as 

 that which divides the premolars of opposite sides. 



One feature is exhibited by the present specimen which is not 

 shown in Pilhol's figure. In the latter the upper true molars 

 appear to have flattened external surfaces to their outer lobes, like 

 those of typical species of Anoplotherium ; whereas in reality these 

 surfaces are much incurved and inclined towards the centre of the 

 crown, so that the whole tooth is practically indistinguishable from 

 a molar of Hyopotamus. This shows that the upper molars from 

 the Lower Oligocene of Switzerland figured by Pictet ^ as Hyopotamus 

 Gresslyi, and subsequently made by myself ^ the type of a distinct 

 species, under the name of H. Picteti, really belong to Dacrytherium 

 and probably to the Quercy species. One of the upper molars of 

 the specimen under consideration is represented in figs. 1, la of 

 the accompanying plate. 



The lower jaw of the new specimen is represented in the 

 accompanying plate, figs. 2, 2a, in which are shown both the outer 



1 Mater, p. la Pal. Suisse, vol. i. — Vert, de la Faune Eocene, Suppl. (1869) 

 pi. xxiv. fig. 5. 



2 aeol. Mag. for 1885, p. 131. 



