FA UNA OF MAMMOTH CA VE—HA Y. 233 



the upper distal portion of the raeros are obsolete, and the eyes are 

 normally developed. 



The individuals from the cave range in length from 1U8 mm. to 35 

 mm., while those from the surface range from 60 nun. to 10 mm. 



Bemarl's. — ^This form of C. hartoni^ which appears to ])e well 

 marked, was found in considerable abundance in Echo River and the 

 River Styx. Ten specimens were collected; one male. Form II, and 

 nine females, two of which carried eggs. In addition to these I have 

 examined a number of specimens from the same localities collected l)y 

 Dr. R. E. Call and others. 



The fact of the existence of cra3"tish with eyes in Mammoth Cave 

 in company with the eyeless C. jf>'(3/ZwY'/V///.s' has frequently been men- 

 tioned by writers on the cave and its fauna but the eyed species has 

 always l)een regarded as a transient or accidental form. It has even 

 been supposed ' that the eyed and eyeless species interbreed so that 

 "the blind form is continually reinforced by new blood from outside 

 the cave."" Dr. Walter Faxon, in speaking of this theory," gives a 

 number of reasons for discarding it, but later in a paragraph on C 

 l^enueidxm testi Hay, which in its appearance is much more like C. hnr- 

 ton'i than is C. i^elluddm, he seems to think that after all such a thing 

 might be possible.^ 



During the course of some carcinological work the writer had occa- 

 sion to review the variations of C. haHoni and spent over a month in 

 the examination of several hundred specimens and considerable addi- 

 tional data. The trip to Manmioth Cave was made largely for the pur- 

 pose of stud3dng the relationship of the cave-inhabiting individuals to 

 individuals living on the surface. 



As is Avell known Cambaras harton! Fabricius is a species with a 

 very extensive range and therefore is subject to much variation. Its 

 habits throughout the range are, so far as I know, practicalh* uniform 

 unless conditions are such as to preclude the possibility of following 

 the customary mode of living. It is a frequenter of cool streams 

 where it lives under the flat rocks or in holes which it excavates among 

 the pebbles. It is rarely found in warm streams or ponds, and when 

 it does occur in such situations is extremely apt to show that this 

 unusual habitat has had eft'ect on its structural character. In its eff'ort 

 to secure its favorite conditions of water, temperature, etc., it is led 

 to ascend the streams, and although this ascent is doubtless made slowly 

 and the attempts at ascent are often stopped or seriousl}' checked by 

 extensive rapids or heav^^ floods, it is nevertheless almost a certainty 

 that through this habit the animal has gone to the very headwaters of 

 many a mountain stream and in favorable seasons has crossed the 



■ iShaler, Mem. Bost. Soc. Nat. Hist., II, 1875, pp. 862, 363. 

 ^Mem. Mus. Comp. Zool., X, No. 4, 18S5, p. 41. 

 •■'Proc. U. S. Nat. Mus., XX, 1898, p. 047. 



