62 



CHARLES DARWIN 



quite incapable, from the socket of the thigh-bone not hav- 

 ing a certain ligament, of jumping even the smallest vertical 

 height. They are very stupid in making any attempt to 

 escape; when angry or frightened they utter the tucutuco. 

 Of those I kept alive several, even the first day, became 

 quite tame, not attempting to bite or to run away; others 

 were a little wilder. 



The man who caught them asserted that very many are 

 invariably found blind. A specimen which I preserved in 

 spirits was in this state ; Mr. Reid considers it to be the effect 

 of inflammation in the nictitating membrane. When the 

 animal was alive I placed my finger within half an inch of 

 its head, and not the slightest notice was taken : it made its 

 way, however, about the room nearly as well as the others. 

 Considering the strictly subterranean habits of the tucutuco, 

 the blindness, though so common, cannot be a very serious 

 evil; yet it appears strange that any animal should possess 

 an organ frequently subject to be injured. Lamarck would 

 have been delighted with this fact, had he known it, when 

 speculating 7 (probably with more truth than usual with him) 

 on the gradually acquired blindness of the Asphalax, ^ a 

 Gnawer living under ground, and of the Proteus, a reptile 

 living in dark caverns filled with water; in both of which 

 animals the eye is in an almost rudimentary state, and is 

 covered by a tendinous membrane and skin. In the common 

 mole the eye is extraordinarily small but perfect, though 

 many anatomists doubt whether it is connected with the true 

 optic nerve; its vision must certainly be imperfect, though 

 probably useful to the animal when it leaves its burrow. In 

 the tucutuco, which I believe never comes to the surface of 

 the ground, the eye is rather larger, but often rendered blind 

 and useless, though without apparently causing any incon- 

 venience to the animal ; no doubt Lanfarck would have said 

 that the tucutuco is now passing into the state of the 

 Asphalax and Proteus. 



Birds of many kinds are extremely abundant on the undu- 

 lating grassy plains around Maldonado. There are several 

 species of a family allied in structure and manners to our 

 Starling: one of these (Molothrus niger) is remarkable from 

 ' Philosoph. Zoolog., torn. i. p. 242. 



