14 



SKETCHES OF CHEAT I OX. 



waifs has a different degree of convexity from the other 

 (Fig. 2), while with mussels both valves are equally con* 



Fig. 1. Fossil bivalve from 

 Trenton Falls ; side view 

 of ventral valve, a. The 

 "beak." 



Fig. 2. Edge view of the 

 two valves, showing 

 their unequal convex- 

 ity and depth. 



Fig. 3. Common River Mussel. View 

 valve, a. The "beak." 



vex (Fig. 4). In fact, the more we study these things, the 

 less they look like mussel-shells — the less they look like 

 any thing else with which we are acquainted. I have 



heard men familiarly 

 call these objects by 

 the name of " clam- 

 shells;"and others 

 they call "snails;" and 

 still other curious struc- 

 )f left tures, frequently en- 

 countered in cultivated 

 fields, they designate as " petrified honey-comb" and " pet- 

 rified wasps'-nests." But a few moments' careful observa- 

 tion suffices to show 

 that these things differ 

 materially from the ob- 

 jects whose names have 

 been bestowed upon ^ 



r Fig. 4. v lew of '• hinge line" of the same, show- 

 them. in S the equal convexity of the two valves. 



It seems unreasonable to suppose, therefore, that these 

 shell-like forms have ever belonged to living animals. 

 They are probably but " mere freaks of nature." Perhaps 

 they have been produced by " the influences of the stars." 



