THE HAMILTON ASSOCIATION. 77 



" conclusions. He infers that the depth of the Primeval Seas in 

 " which the Mountain Limestone was formed, did not exceed fifty 

 " fathoms. To this opinion he is led by observing that in the exist- 

 "ing seas, "The Testacea," which have colors and well defined 

 " patterns, rarely inhabit greater depths than fifty fathoms, and the 

 " greater number are found where there is most light in very shallow 

 "water, not more than two fathoms deep." 



There are even examples in the British Seas — "Testacea" 

 are always white or colorless when taken from below one hundred 

 fathoms, yet individuals of the same species if taken from shallow 

 zones are vividly striped or "banded." 



''Lingula Ingrus " of the Niagara limestones, described and 

 figured by Dr. Spencer, is black or horny in the only three specimens 

 collected. Strictly speaking it belongs to the "chert beds." Now, 

 as a general rule, the fossils of these beds present a divarfed appear, 

 ance like many contained in shales, even the Trilobites being quite 

 stunted in growth. We know when the chert was deposited, there 

 was an unusual quantity of silex held in solution in the water, and 

 this or heated springs, derived from the Laurentian Highlands, 

 may have exercised much the same unhealthy influence as the 

 brackish water of the Baltic of our own day does on its inhabitants. 

 The late lamented Dr. Carpenter examined many of the specimens 

 brought to light by the deep sea explorations of the recent 

 Challenger Expedition. Live specimens, he remarks, were 

 obtained from depths verging on three miles; the result was to show 

 that, while there is no depth at which animal life cannot exist, the 

 deeper you go, the more scanty such life becomes. Temperature 

 has a great deal more to do with animal life than the pressure of 

 water resulting from depth of the sea, and, while in the cold under- 

 flow the same forms of life are found as elsewhere, the specimens 

 are greatly dwarfed. 



It seems a little singular that such a large Lingula as "Lingens" 

 should make its appearance during the deposition of " the chert," 

 and that one of the most minute members of the same family occurs 

 in a true limestone layer here. It may be imagined that the latter is 

 merely the young of a more fully developed Lingula, but as it seems 

 confined to certain beds and has apparently no larger one associated 

 with it, scattered as it is through three or four distinct layers of con- 



