Fossil Bones of the Megalonyx. 167 



ed, all the ungueal phalanges were furnished vvhh very large 

 ones, though they are generally found broken off. In these 

 remarkable sheaths the foot resembles that of the Megatherium, 

 which had them so large as to encase the phalanx for more 

 than half its length. In the Megalonyx the sheath was not 

 complete, as it appears to have been open above, along the 

 back of the bone ; a circumstance which is also observed in 

 the Mijrmccophaga juhata. The use of these sheaths was to 

 strengthen and support the great claws, the base of which they 

 firmly embraced. 



The extreme rarity of these remains, and the unusual kind 

 of animal which they bespeak, confer an interest upon every 

 additional discovery. The bones now presented to the Lyceum 

 had been preserved, for several years, as curiosities, at the 

 mansion of the late President JVIonroe, and were thought to be 

 " petrified lobster's claws." Their origin is no longer known, 

 but to judge from their colour and appearance, they have been 

 preserved from decay in the same manner as those first described 

 by Mr. Jefferson, and very probably belonged to the same 

 skeleton; of which many bones were carried off and dispersed 

 before the discovery became known to him. It is a circum- 

 stance in favour of this conjecture, tliat they now prove to have 

 belonged to the corresponding limb of the opposite side. Not- 

 withstanding an appearance of antiquity, they are hard and 

 sound, and their composition is apparently unchanged. 



The following is a general view of the parts belonging to 

 the skeleton of the Megalonyx that have been hitherto disco- 

 vered, and of the affinities which they indicate with the other 

 animals of the order Edentata.* 



* It Avill be observed that I speak of these bones as all belonging to 

 one species of animal. Dr. Harlan and Mr. Rafinesque, on the contrary, 

 are of opinion that those found in Kentucky belonged to a different spe- 

 cies from the Megalonyx of Jefferson. Dr. H. founds his opinion, 



1. Upon the different proportions, and the longitudinal grooves or 

 flutings observable in the teeth from Kentucky. 



2. The different form and proportions, and greater strength of the un- 

 gueal phalanges, and their having a notch instead of avascular foramen. 



Vol. hi. 22 



