EDENTATA. 



221 



■ To wliat cause should their extinction be referred ? It may have been simplj- that their time 

 was up, — that the life of the genus had run its course ; or if wo look for a more direct cause, 

 it would not be difficult to find one in the glacial cold, were it not for the statement which has 

 been made on the best authority that, like the Mammoth and Mastodon (animals which seem to 

 have owed their origin to the change at the glacial ejjoch), these Edentates sur\-ived that time. 



Dr. Falconer, in his paper on " Fossil Elephants," says : " Of two asserted facts, which it was 

 of the utmost importance to determine with accuracy, one appears to have been cleai'ly established : 

 namely, that the extinct Edentate and Proboscidean fauna of the United States existed long after 

 the deposition of the northern di-ift. This was put beyond doubt by Lj-ell many years ago ;"* and 

 then he goes on to cite instances where the Mastodon Ohioticus (which was within the special 

 scope of his paper) was certainly so found : but he gives no instance, nor does he refer to any 

 authority, in support of his statement regarding the Edentata ; and as to them, Lyell says in 1865, 

 " Whether the ' loes ' and other fresh- water and marine strata of the Southern States in which 

 skeletons of the same Mastodon are mingled with the bones of the Megatherium, Mylodon, and 

 Megalonyx, were contemporaneous with the drift, or were of subsequent date, is a chronological 

 question still open to discussion." f Supposing it to have been contemporaneous with its early 

 stage there is nothing inconsistent with their having died imder the cold, or they may have passed 

 their time in exile in the trojjics dming its continuance, and on its retreat have returned to their 

 old place, but, unable to stand the modified climate, soon dropped off. 



I have endeavoured to arrive at some conclusion on the subject, and although it becomes me 

 to speak with the greatest diffidence in a matter on which professed geologists have come to 

 a different opinion, I may be allowed to express a doubt that the North American Megatheroids 

 did sm-vive the period of the drift, that is, the glacial epoch. I believe that the general under- 

 standing that they did so, has arisen from their bones having been in one or two instances found 

 in company with those of the Mastodon and other animals which did survive that epoch, but that 

 these exceptional cases are capable of explanation. Professor Owen's memoir on the " Megathe- 

 rium," and Leidy's on the "Extinct Sloths of North America," supply us with notes of every 

 locality where their remains have been found, and an examination of the age of the deposits at 

 each of these places gives the following residt : + — 



Species. 



Locality. 



Lima (ITOO) (no particulars) 

 Paraguay (179.")) (no particulars) 



Formation in which Ke- Before on after Gijicial 



MAINS FOUND. 



JMegathcrium — Banks of the River Luxan near Tliocene 



Cuvieri Desm. (Ameri- Buonos Ayres (1789) 



cauum Uiceii) 



Unknown 



Uraguay, in the bed of the Que- Pliocene 

 guay(l82:j) 



EPOCH. 



Before glacial epoch. § 



Unknown. 



Before glacial epoch. 



* Fai.conf.b, np. cit. p. 02. § For shortness T call the pliocene beds '■ before the glacial 



t Lyell's " Kleiuents of Geology," Loiidon, 1865. epoch," although, stiictly speaking, I believe its cold began to 



} This list has had the advantage of being submitted to show itself in the pliocene times. In using that pluase here, I 



Dr. Leidy pre\ioas to publication. merely mean before the glacial epoch had put on its full rigour. 



