282 IN LOWER FLORIDA iVILDS 



inches. It is believed to be a dwarf variety of 

 Spisula solidissima, which the collector will find 

 in just as great abundance from Cape Hatteras 

 northward. It is probable that on account of 

 climate our southern form is less robust and 

 brighter colored than its northern relative. On 

 the other hand Venus mercenaria, the common 

 hard-shell edible clam of the New Jersey and Long 

 Island coasts, reaches a length of three inches, 

 while in the bays along our southwest coast it 

 becomes more than twice that size and attains the 

 preposterous weight of five pounds. It is some- 

 times considered a mere variety of mercenaria and 

 again is ranked as a species. In these two cases 

 climate seems to work both ways. No doubt 

 conditions in the north are more favorable for 

 the Spisula than along the Florida coast, while 

 the subtropical waters of the Gulf of Mexico 

 exactly suit the large clam which grows only in a 

 stunted form in the cold northern ocean. Macro- 

 callista gigantea and M. maculata have large, 

 beautifully maculated, polished shells; Cardium 

 magnum, C. isocardia, and C. Icevigatum are abun- 

 dant, handsome forms, the former as large as a 

 man's fist. There are elegant circular Dosinias 



