Miscellaneous. 397 



MISCELLANEOUS. 



Notice of new Equine Mammals from the Tertiary Fonnation. 

 By Professor 0. C. Maesh. 



In this jDaper Prof. Marsh describes a very interesting series of 

 remains of equine animals from the Tertiary deposits of the\Ye8tern 

 Territories, the fruit of the explorations of a party sent out by Yale 

 College. 



The American Eocene mammals of this group belong to a genus 

 lately established by Prof. Marsh under the name of Orohippns ; it 

 is nearly allied to Anchitherium, but differs by "having four 

 functional digits in the manus " and by the absence of the ante- 

 orbital fossa. The dentition is very like that of Anchitherium, and 

 its formula is as follows : — 



Incisors |, canines \, premolars -i, molars -|. 



There is a long diastema ; and the canine is large. The known 

 species ai*e Orohippus gracilis, Marsh, 0. pumilus, Marsh, 0. ayihs, 

 Marsh, and 0. major, sp. n., all fi'om the Eocene of Wyoming and 

 Utah. 0. major Avas about the size of a fox. 



A form intermediate between Orohipjpus and Anchitherium is 

 described as constituting a new genus under the name of Miohippus 

 annectens. It has no anteorbital fossa ; but there are only three 

 digits in the raauus. The dental formula is the same as that of 

 Orohippiis ; and the intermediate lobes of the upper molars are more 

 completely separated than in Anchitherium. Miohippus annectens 

 is from the Miocene of Oregon. It was rather larger than a sheep. 



Anchitherium anceps and A. celer are two new species. The 

 former, about as large as a sheep, is from the Miocene of Oregon ; 

 the latter, a small species, about two thirds the size of A. Bairdi, is 

 from the Miocene of Nebraska. 



Equus parvulus. Marsh (Sill. Journ. xlvi. p. 374), is now referred 

 by the author to Protohippus, Leidy. It is from the Pliocene 

 deposits of Nebraska ; and its remains indicate an animal about 

 2| feet in height. Another species, Protohippus aims, sp. n., from 

 the Pliocene of Oregon, is represented only by teeth ; but these 

 indicate such differences from the dentition of other species that 

 the animal will probably prove to be generically distinct. 



Pliohippus is a new geniis allied to Equus and having only 

 splint bones in place of the lateral hoofs, but closely resembling 

 Protohippus in its dentition, and possessing a large anteorbital fossa. 

 Its dental formula is as follows : — 



Incisors f^, canines i, premolars i, molnrs ^}. 



Pliohippus 2}ernix, sp. n., of which a considerable part of the 

 skeleton has been exhumed from the Pliocene sands of the Niobrara 

 river, Nebraska, was about the size of an ass. A second, and 

 apparently somewhat larger species, P. robustus, sp. n., was obtained 

 from the same locality. 



The teeth of a new species of the supposed Miocene genus ^1/t- 

 Ann. & Mag. N. Hist. hJcr. 4. Vol. xiii. 28 



