DIVERSIFIED TYPES FOUND EVERYWHERE. 19 



the diversity of animals and plants living together in the 

 same region may be, can be ascertained by the perusal of 

 special works upon the Zoology and Botany of different 

 countries, or from special treatises upon the geographical 

 distribution of animals and plants. 1 I need not enter, 

 therefore, into further details upon this subject, especially 

 since it is discussed more fully below. 2 



It might, perhaps, be urged, that animals living toge- 

 ther in exceptional conditions, and exhibiting structural 

 peculiarities apparently resulting from these conditions, 

 such as the blind fish, 3 the blind crawfish, and the blind 

 insects of the Mammoth Cave in Kentucky, furnish un- 

 controvertible evidence of the immediate influence of 

 those exceptional conditions upon the organs of vision. 

 If this, however, were the case, how does it happen that 

 that remarkable fish, the AmUyopsis spdceus, has only 

 remote affinities to other fishes ? Or were, perhaps, the 

 sum of influences at work to make that fish blind, capable 

 also of devising such a combination of structural charac- 

 ters as that fish has in common with all other fishes, with 



1 SCHMARDA, Die geographische nee; 2 vols., 8vo., Paris, 1855. Re- 



Verbreitung der Thiere ; 3 vols. 8vo., ferences to special works maybe found 



Wien,1853. SWAINSON (W.),ATrea- below, Sect. 9. 



tise on the Geography and Classifica- 2 See below, Sect. 9. 



tion of Animals; London, 1835, 1 vol. 3 WYMAN (JEF.), Description of a 



12mo. ZIMMERMANN (E. A. G.), Spe- Blind Fish, from a Cave in Kentucky, 



cirnen Zoologize geographic^, Quad- SILLIMAN'S Jour., 1843, vol. 45, p. 94, 



rupedum domicilia et rnigratioues and 1854, vol. 17, p. 258. TELL- 



sistens; Lugduni-Batav., 1777, 1 vol., KAMPF (Tn. G.), Ueber den blinden 



4t . HUMBOLDT, Essai sur la geo- Fisch der Mammuthhohle in Ken- 



graphie des Plantes ; 4to., Paris,1805; tucky, in Miiller's Archiv, 1844, p. 



and Ansichten der Natur, 3rd edit., 381. TELLKAMPF (Tn.G.), Beschrei- 



12mo., Stuttgardt and Tubingen, bung einiger neuer in der Mammuth- 



1849. ROBERT BROWN, Generate- hohle aufgefundener Gattungen von 



marks on the Botany of Terra Aus- Gliederthieren, WIEGMAN'S Archiv, 



tralis; London, 1814. SCHOUW, 1844, vol. i, p. 318. AGASSIZ (L.), 



Grundziige einer allgemeinen Pflan- Observations on the Blind Fish of the 



zengeographie; 1 vol. Svo., with atlas Mammoth Cave, SILLIMAN'S Journal, 



in fol., Berlin, 1823. ALPH. DE CAN- 1851, vol. 11, p. 127. 

 DOLLE, Geographic botanique raison- 



c 2 



