CAMKARUS. 41 



College, Kentucky, published in the ' Belfast Commercial Chronicle' of Jan. 1, 

 1844, where it occupies two columns, but the source whence it was obtained 



is not acknowledged The crayfish and ' crickets ' are stated in the 



letter already noticed [the Rev. Win. Murphy's ?] to be blind, but this is 

 erroneous. Both species have eyes. Our specimen of the crayfish wants 

 both the claws, but is otherwise perfect, and agrees with. the description of 

 the Astacus Bartoni Fabr., given in Milne Edwards's ' Histoire des Crustaces,' 

 Vol. II. p. 331. The length there attributed to the species is 3 inches ; the 

 specimen before us is 2j inches in length from the point of the rostrum to 

 the extremity of the caudal plates." 



The description of Astacus Baiionii by Milne Edwards, here referred to, 

 is in reality a description of Astacus affiim Say ; but as C. Bartonii is the 

 only eyed crayfish known to inhabit the Mammoth Cave, it was probably 

 the species in Thompson's hands. Tellkampf's type (a male, form I.) was 

 more fully described by Erichson, and was seen by Hagen in the Berlin 

 Museum in September, 1870. 



The presence in the Mammoth Cave of a crayfish with well-developed 

 eyes, together with the blind species, was noticed by Prof. B. Silliman, Jr., 

 in 1850. In a letter to Professor Guyot, dated Louisville, Nov. 8, 1850, 

 printed in the American Journal of Science and Arts, 2d Ser., Vol. XL, 

 May, 1851, he says (p. 336) : - 



" The crawfish, or small Crustacea inhabiting the rivers with the fish, 

 are also eyeless and uncolored, but the larger-eyed and colored crawfish, 

 Avhich are abundant without the cave, are also common at some seasons in 

 the subterranean rivers Among the collections are some of the larger- 

 eyed crawfish which were caught by us in the cave." 



I have now before me specimens of C. pellucidus and C. Bartonii from the 

 Peabody Museum of Yale College (Nos. 1814, 1815), collected by Professor 

 Silliman in the Mammoth Cave. More recently, C. Bartonii has been fre- 

 quently captured there. 



The association of C. pellucidus and C. Bartonii in the Mammoth Cave, 

 and the fact that cave specimens of the latter are often very light colored, 

 led Professor N. S. Shaler * to conclude that the two species were connected 

 by transitional forms, and that the blind form was derived from the present 

 outside fauna of the region. He even goes so far as to suppose that the 

 blind form, C. pellucidus, is continually reinforced by interbreeding with the 



* Mein. Boston Soc. Nat. Hist., II. 362, 363, 1875. 

 6 



