

74 ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



* 



The fossil remains here described were discovered by Mr. Darwin in the 

 same bed of partly consolidated gravel at Punta Alta, Northern Patagonia, as 

 that in which the lower jaws of the Toxodon and Mylodon were imbedded. 

 The parts of the skeleton about to be described were discovered in their natural 

 relative position, as represented at PI. XX., indicating, Mr. Darwin observes, that 

 the sublittoral formation in which they had been originally deposited had been sub- 

 ject to little disturbance.* They include the cranium, nearly entire, with the teeth 

 and part of the os hyoides; the seven cervical, eight of the dorsal, and five of the 

 sacral vertebrae, the two scapulae, left humerus, radius and ulna, two carpal bones, 

 and an ungueal phalanx ; both femora, the proximal extremities of the left tibia 



and fibula, and the left astragalus. 



The principal parts of the cranium which are deficient are the anterior 

 extremities of both the upper and lower jaws, the os frontis, sethmoid bone, and 

 the whole upper part of the facial division of the skull ; but sufficient remains to 

 show that the general form of the skull resembled an elongated, slender, sub-com- 

 pressed cone, commencing behind by a flattened vertical base, slightly expanding 

 to the zygomatic region, and thence gradually contracting in all its dimensions to 



the anterior extremity. 



The Cape Ant-eater (Orycteropus), of all Edentata, most nearly resembles 

 the present fossil in the form of its cranium, and next in this comparison the 

 great Armadillo (Dasypus gigas, Cuv.) may be cited : on the supposition, there- 

 fore, that the correspondence with the above existing Edentals observable in the 

 parts of the fossil cranium which do exist, was carried out through those which 

 are defective, the length of the skull of the Scelidothere must have been not less 

 than two feet. If now the reader will turn to PI. XX. he will see that this 

 cranium is singularly small and slender in proportion to the rest of the skeleton, 

 especially the bulky pelvis and femur, of which bones the latter has a length of 

 seventeen inches, and a breadth of not less than nine inches ; the astragalus, 

 again, exceeds in bulk that of the largest Hippopotamus or Rhinoceros ; yet the 

 condition of the epiphyseal extremities of the long bones proves the present 

 fossils to have belonged to an immature animal. Hence, although the Scelido- 

 there, like most other Edentals, was of low stature, and, like the Megatherium, 

 presented a disproportionate development of the hinder parts, it is probable, 

 that, bulk for bulk, it equalled, when alive, the largest existing pachyderms, not 

 proboscidian. There is no evidence that it possessed a tesselated osseous coat 



of mail. 



I shall commence the description of the present skeleton with the cranium. 



* 



This beach is covered at spring tides ; many parts of the skeleton were encrusted with recent Flustrce, 



and small marine shells were lodged in the crevices between the bones. 



