82 The Williams Collection of Shells 



Ch. damaecornis. There are also specimens of fossil 

 Chamae. 



Again we pass a number of families few in species, 

 including the Tridacnidae (nearly all the species of 

 Tridacna and Hippopus are here, huge, overgrown, 

 but far from (ungraceful), Lucinidae (quite a 

 number of species, of which Corbis sowerbyi, Reeve, 

 from China, deserves special mention on account of 

 great rarity) and others typified by the genera Kellia, 

 Scintilla, Solemya, Crassatella, Gouldia, and Astarte, 

 besides the Carditidae and Cypricardiidae. 



The beautiful pearl shells from our own lakes and 

 streams, to which belongs the suggestive name Union- 

 idae, have peculiar interest. No other family is as 

 distinctively and characteristically American. Let 

 others seek these shells in a war of extermination, to 

 mutilate and change them into objects of personal 

 adornment, but let us study them and enjoy the rich 

 iridescence of their nacre. For there are here, not 

 merely a fine cabinet series of hundreds of natural shells, 

 but a half a hundred or more of hand-polished speci- 

 mens, the very best obtainable. Some of the finest of 

 these fresh-water clams came from the boiling rapids 

 of the Baraboo River in Wisconsin, obtained by divers 

 at the risk of their lives. The collection includes Lewis's 

 type of JJnio brevis and a cotype of £7. bursapastoris, 

 B. H. Wright. Burtonia tang any ikensis, Smith, illus- 

 trates a strange form of this group from Central Africa. 



