Baker — The Molluscan Fauna of McGregor, Iowa. 251 



was permitted to buy about a bushel and a half of clams for two 

 dollars but was cautioned not to take a pearl, only the shells 

 being salable. It was curious to see the value placed upon an 

 unopened clam. Offers of three, four or five dollars for a 

 small lot of freshly-caught, living clams were scornfully re- 

 fused. The value placed upon distorted or diseased clams, 

 called by the fishermen " cripples," was fairly ludicrous. 

 They have a belief that a cripple is almost always sure to con- 

 tain a pearl and they are not always disappointed in this be- 

 lief, for many distorted individuals do contain fine pearls. 

 Two beautiful pearls were shown the writer by a resident of 

 McGregor, one nearly a third of an inch in diameter and of 

 exquisite luster and color, being valued at fifteen hundred 

 dollars, and another smaller one at about three hundred 

 dollars. These had been recently secured from the clams 

 near McGregor. 



The writer believes, after a careful study of the mussel 

 fishery at this place, that the large number of cripples en- 

 countered is due largely to the crowfoot dredge. Many 

 shells have the valves curiously distorted, as though broken 

 by accident, and it seems quite probable that young mussels 

 which were broken by the hook should have grown and be- 

 come distorted in consequence of the injury. The broken 

 valves would also offer an effective means of commun- 

 ication to the inside of the clam, and sand, the eggs of 

 mollusks and parasitic animals could easily find entrance 

 and produce further distortion, or, perchance, a pearl or 

 two. 



A sad and suggestive feature of the mussel fishery at this 

 place is the waste of shells which are of no value either for 

 their shells or as containing pearls, and are thrown upon the 

 shore when the catch is picked over. These consist of 

 Anodonta, thin-shelled Lampsilis, Alasmidonta and any small 

 or thin-shelled clam. In some places the shore is fairly paved 

 with these shells. Such wanton destruction grieves the true 

 naturalist. 



It may be of interest to tabulate some of the species which 

 contained the greatest amount of abnormal pearly matter and 



