132 AMERICAN JOURNAL 



the size of Pliy tophaga. Enhydra Odoboena ; Succinea oblonga, 

 S. amphibia. 



Among cold-blooded terrestrial animals, the largest species 

 are always tropical, although the largest Mollusca in general 

 are tropical — {Tridacna, Cassis, Fusus incisus, Martyn) ; this is, 

 however, not the case in each family ; thus the largest Soleriy 

 Modiola, Plagiostoma, Pecten, Haliotis, or 3Iytilus are found in 

 sub-polar seas. The Mediterranean, although only a sub-tropi- 

 cal sea, offers species much larger than the truly tropical seas, 

 as Jianella, Pinyia. " Animals whose chief metropolis is in a 

 temperate climate, become smaller when they extend their limits 

 into a warmer region, and vice versa.'' — Sws. on Classification, 

 p. 285.* 



XIX. " Multiplicity of organs indicates inferiority in struc- 

 ture." — Owen. Hexapods are inferior to Quadrupeds — Multi- 

 peds inferior to Hexapods. Suckers of Echinodermata may be 

 considered the loAvest kind of locomotive organs ; Polyommatous 

 inferior to binocular. 



XX. Color and its various patterns offers some of the most 

 important means of distinguishing species, and even genera. 

 The same color is often common to animals of the most different 

 orders and classes living in the same province. f The land 

 shells in the rainless regions are thus always white. The Tro- 

 choidea in the Chilian province are predominately black. The 

 oceanic animals are nearly all bluish and pellucid. Whether the 

 different colors indicate relative superiority or inferiority, is not 

 yet made out. Oken| considers the yellow color of flowers to 

 indicate inferiority. The following table shows the concordance 

 of the colors with the form in various families of shells : 



The third line contains genera with unicolor species, com- 

 paratively few in number ; but nearly every three species are 

 established as a subgenus. 



The second line affords genera very numerous in species with 

 a variegated pattern, and very difficult to divide into natural 

 subgenera. 



The genera in the first line are composed of species few in 

 number, generally with undulated lines, and often spinous. 



* And Jeffrey's British Molkisca. 



t Synontological Relations of Lorenz Wiener, Sitzungsbericht, 1858, 

 p. 29. 



X Oken, Naturphilosophie, p. 188. 



