488 



THE AMERICAN NATURALIST [Vol. XLII 



" In the individual the effects are shown in the disturbance of the 

 laws of growth, producing abnormal or premature weakness or in the 

 natural exhaustion of the powers of growth causing senility. A wound 



classified, since it is primarily a severe shock to the system which lays 

 additional burdens upon the powers of growth and is usually followed 

 if severe by retrogressive metamorphoses or premature old age . . . 

 normal old age simply expresses the norm d wearing out of the powers 

 of vitalized tissue to sustain itself against the perpetual friction of ex- 

 isting physical surroundings. . . . AVhen we compare these effects of 



of the individual with the corresponding distortions and decrease in 

 size of the retrogressive sub-series there is a certain similarity which 

 leads to the supposition that the latter are also probably due to an 

 mi favorable environment." 43 



//. At Storm King, about fifty miles above New York, 

 was found in drilling a series of holes across the Hudson, 

 an apparently dwarf fauna including only two species, 

 Mulinia lateralis (Say), of which there are hundreds of 

 specimens and Trivia trivittata Say, of which there are 

 but few specimens in our collection. 



(These fossils were obtained by Professor W. 0. 

 Crosby in February, 1D0S, and through his kindness these 

 facts are presented.) 



These were found in but one drill hole, though prob- 

 ably the same species are present in the others but 

 passed unnoticed in the drilling. They occur 620 feet out 

 in the river from the Storm King shore, 40 feet below 

 the bed of the river, i. e., about 120 feet below the present 

 river or sea level at that point. The Hudson is brackish 

 at this point and as far north as Poughkeepsie, as is evi- 

 denced by the absence of ice houses below Poughkeepsie. 

 "Whether in the present bed of the stream there are any 

 marine forms growing was not ascertained. The heavier 

 sea water might still come up in sufficient amount to 

 furnish a marine habitat even under quite fresh surface 

 conditions. This dwarf fauna in the abundance of 

 Mulinia lateralis suggests Pleistocene age. 



These two species live at present off the New England 



" Hyatt. Loc. cit., p. 15. 



