314 THOMAS J. HEADLEE. 



periment in a common wash-tub to which I shall refer in detail 

 later. 



In these experiments when a mussel was found, whose gills 

 contained mud, we considered that he was the victim of bottom 

 conditions. So far as our experience goes, the presence of mud 

 in the gills is always followed by the death of the animal if he 

 cannot free himself from the environment which is responsible for 

 his mud-choked state. Beginning with the least successful, the 

 following forms are given in the order in which they stood the 

 bottom test, assuming that the more mud they contained, the less 

 well had they withstood the soft bottom : The dark form of U. 

 lit f coins, U. ritbiginosus, the medium form of U. httcolus, the light 

 form of U. lutcolits, U. subrostratus, A. grandis and A. cdentnla. 

 U. glans and U. fabilis have not been listed because we were 

 unable to obtain a sufficient number for investigation. 



Since the mussels taken directly from the beds differed from 

 those taken from the baskets placed on dark mud in that the 

 latter showed from sixty to ninety per cent, of the total number 

 choked with mud, the question might be raised, is not the pres- 

 ence of mud due to the animal being confined in a basket, where, 

 perhaps, he cannot place himself most advantageously ? The 

 confining of the mussels in the baskets might operate unfavorably 

 through crowding or through lack of soil in which to assume 

 their normal position. The basket in all cases was made large 

 enough to give each mussel more room than he would have on a 

 crowded bed. It is true that on a hard bottom the basket would 

 prevent the animal from burrowing in the soil, but on the soft 

 bottom he would have from two to six inches of it. The baskets 

 were weighted so that they would be forced down into the soft 

 bottom. We set a basket on a gravelly sand bottom, but it was 

 lost just before we would have killed and examined its contents. 

 However, during the forty-five days of its submersion before its 

 loss, none of the mussels died a condition which obtained in 

 but one of the baskets planted on mud, and this one was in but 

 twenty feet of water where the bottom was not so soft as in the 

 deeper parts. The mussels in the basket on gravelly sand were 

 subjected to more injurious conditions by the basket itself than 

 were those of the others, for the wire in this case could not sink 



