. Grotta di vertebrati di America; uno studio in evoluzione degenerativa. Animali cavernicoli; evoluzione. 26 Ciechi vertebrati e i loro occhi. La grotta di ratto e i suoi occhi". La grotta di ratto, Neotoma mai^iskr, gamme a est a sud di New York e del sud di Alabama, e non è limitata a grotte. Essa vive in "scogliere, grotte e sporgenze rocciose delle montagne che scendono in pianura, dove grotte calcaree permettersi la sicurezza IT." In bianco della grotta, nei pressi di Mammoth Cave, Kentucky, ha i suoi nidi vicino all'ingresso, nella regione di crepuscolo. In Mammoth Cave ho trovato nella cupola mammut, e si verifica anche più lontano i

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. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Evolution. 26 BLIND VERTEBRATES AND THEIR EYES. THE CAVE RAT AND ITS EYES.' The cave rat, Neotoma mai^iskr, ranges eastward to southern New York and south to Alabama, and is not confined to caves. It lives in "cliffs, caves, and rock ledges of the mountains, descending into the lowlands, where limestone caves afford it security." In White's Cave, near Mammoth Cave, Kentucky, it has its nests near the entrance, in the twilight region. In Mammoth Cave I found it in Mammoth Dome, and it occurs also farther in, far removed from the twilight area. Rhoads (Jour. Cin. Soc. Nat. Hist., xix, No. 2, 55, 1897) says of it: Any suspicion of blindness or deficient eyesight, such as is exemplified in some of the lower orders of animal life in the cave, can not attach to this mammal. As in all the more strictly noc- turnal rodents, the eyes of this species are greatly developed; nevertheless, they are able to make most intelligent use of them in broad daylight, if need be. In his "Origin of Species, " sixth edition, vol. i, page 171, Darwin says that the eyes of Neotoma of Mammoth Cave are "lustrous and of large size; and these . Fig. I. (a) Eye of Mammoth Cave Rat. (A) Eye of Common Gray Rat. animals, as I am informed Ijy Professor Silliman, after having been exposed for about a month to a graduated light, acquired a dim perception of objects." The cave rat, Neotoma, is still abundant in Mammoth Cave. Its tracks are numerous, and in places little paths have been made by the rats where they run backward and forward along ledges of rock. Since, however, a track once made in a cave remains unchanged by wind or weather, the abundance of rats, as judged by their tracks, may be misleading. A number of traps were set in the rotunda. During three days one trap was sprung and one had the bait removed. No rats were caught in the traps and none were caught alive. The author discovere

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• bookcentury1900
• bookdecade1900