320 ANNUAL OF SCIENTIFIC DISCOVERY, 



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unable satisfactorily to determine. The specimens present so much differ- 

 ence in condition of preservation, or change in structure ; so much variation 

 in size, from that of the more ordinary horse to the largest English dray 

 horse; and such variableness in constitution, from that of the recent horse 

 to the most complex condition belonging to any extinct species described, 

 that it would be about as easy to indicate a half dozen species as it would 

 two. 



" Under the circumstances, I would characterize the extinct horse of the 

 United States as having had about the same size as the recent one, ranging 

 from the more ordinary varieties to the English dray horse, with molar teeth, 

 frequently comparatively simple in construction, but with a strong disposi- 

 tion to become complex. 



" Among the number of teeth of the horse in Prof. Holmes's collection, 

 labelled as coming from the post-pleiocene deposit of Ashley river, there are 

 several, which, from their size, construction, and condition of preservation, 

 I feel convinced are of recent date ; and these, no doubt, became mingled 

 with the true fossils of that formation where it is exposed on the Ashley 

 river, in which position I personally found undoubted remains of the recent 

 horse, and other domestic animals, and objects of human art, mingled with 

 remains of fishes, reptiles, and mammals, washed by the river from the 

 banks, composed of eocene and post-pleiocene deposits. 



" Teeth of an extinct species of horse, however, undoubtedly belong, as 

 true fossils, to the post-pleiocene formations in the vicinity of Charleston. 

 These are usually hard in texture, stained brown or black from the infiltra- 

 tion of oxide of iron, sometimes well preserved, but more frequently in a 

 fragmentary condition and water-worn. Generally, they are not larger than 

 the teeth of the more ordinary varieties of the domestic horse, and some- 

 times are quite as simple in the plication of their enamel; but usually are 

 more complex, and sometimes exceedingly so. 



" Among the specimens collected by Prof. H., is a first superior molar 

 tooth, neither larger nor more complex in structure than the corresponding 

 tooth of the recent horse. This specimen, which is dense and jet-black in 

 color, was obtained from a stratum of ferruginous sand, two inches thick, 

 exposed on the side of a bluff, on Goose Creek, about twelve miles from 

 Charleston. 



" Having expressed a desire to see the locality from which the tooth just 

 mentioned was obtained, Prof. Holmes afforded me the opportunity of doing 

 so. The bluff is about thirty feet high ; its base is formed of a pleiocene 

 limestone, about fifteen feet thick, and composed of the debris of marine 

 shells ; above this is the stratum of ferruginous sand, of post-pleiocene age, 

 containing numerous pebbles and rolled fragments of bone, all blackened like 

 the tooth obtained from the same position. Overlying the latter stratum 

 there is a layer of stiff blue clay, about two feet in thickness, and above this 

 there are about twelve feet of sand and earth-mould. 



" A remarkably well-preserved specimen of an upper molar tooth, jet-black 

 in color, and an incisor, yellow and quite friable in texture, both belonging 

 to the extinct horse, from North Carolina, have been submitted to my in- 

 spection by Professor Emmons. Among the most interesting of the fossils 

 discovered by Prof. Holmes, in the post-pleiocene beds of the Ashley river, 

 are two molar teeth of a species of the equine genus Hippotherium. These 

 are the first remains of the latter discovered in America, and they indicate 

 the smallest known species. Both specimens are from the upper jaw; and 



