302 Monograph of the Gasteropoda. 



anomalous and inconsistent features can not be reconciled upon any 

 theory of indigenous growth. Any view of the subject, based upon 

 speculative or theoretical grounds, must be held open to modification 

 by the results of actual investigation. Yet, this would seem to be a 

 fair deduction from all the facts known, and reconciles many appar- 

 ently conflicting inferences drawn from relics found in and about the 

 works themselves. 



Whether this earlier race were identical with those whose remains, 

 closely resembling the singular Central-American bas reliefs, were 

 found in the catacombs of the arid salt desert of Atacama, and pro- 

 nounced by Dr. Morton to be a race differing in important physical 

 characteristics from all known types of human beings, we perhaps shall 

 never know with certainty. But there is every reason to hope 

 that when the field shall have been more thoroughly gleaned, and the 

 remains more intelligently classified, and when the gloomy coverts of 

 Central American forests shall have yielded up all their treasures ; and, 

 especially, when the hieroglyphics shall have received the careful study 

 of scholars familiar with Egyptian and other ancient modes of thought 

 and expression, instead of neglect and indifference, that the history of 

 the ancient dwellers of Ohio will be told as a component part of the 

 great civilized race, whose primal seat was in tropical America, or, 

 possibly, in the lost Atlantis of Plato. 



Until these explorations can be made, a labor which seems to be the 

 peculiar province of antiquarian societies or of government, we must be 

 content to regard the problem still unsolved and wander yet longer in 

 the mazes of conjecture, seeking the clue which will lead us to a knowl- 

 edge of the true ethnic relations and history of the Mound Builders, 

 whose struggle against the tide of invasion, which finally overwhelmed 

 and exterminated them, is attended by silent though eloquent witnesses, 

 like Fort Ancient and other similar works. 



Monograph of the Gasteropoda of the Cincinnati Group. 



This class of Mollusca takes its name from the broad, muscular, disk- 

 like foot attached to the ventral surface, upon which the animal creeps 

 slowly along, with a gliding motion. This movement is produced by 

 the successive expansion and contraction of the foot, which is well 

 shown by the common snail when climbing a pane of glass. Tlie 

 shell, with which the animals are furnished, as in other 3£ollusca, is 

 secreted by the edge of the mantle, and usually forms a conical, spirally 

 twisted tube. The right side of the Gasteropoda is usually the largest, 



