240 WILLIAM RAY ALLEN. 



rhythmic loss and renewal of the style in tidal forms has no 

 parallel in freshwater species. 



11. The feeding of specific substances in high concentration 

 never produces a renewal of the crystalline style unless such sub- 

 tances have a food value. No indication was observed that the 

 stimulus for its secretion is a mechanical one. 



12. The style is much less readily formed in autumn or winter. 

 That temperature is responsible is shown by experiments in which 

 starved mussels were fed a concentration of plankton in water of 

 high and low temperature, respectively. 



13. A very small amount of plankton is sufficient to stimulate 

 style formation. Also only a short time is required. 



14. The labial palps are the primary assorting mechanism. 

 The gills are of considerable importance in this matter also. 



15. Sand is never ingested, at least by lake forms, and mud but 

 slightly. Much less inorganic debris finds its way into the 

 stomach than would be the case if selection were not exercised bv 

 the gills and palps. 



1 6. The cilia of the alimentary canal are unable to move coarse 

 materials, or to maintain a stream of sand or heavy mud. 



17. Gravidity of the gills is a serious hindrance to the respira- 

 tory and alimentary activities. 



LITERATURE CITED. 

 Allen, W. R. 



'14 The Food and Feeding Habits of Freshwater Mussels. BIOL. BULL., 



Vol. 27, pp. 127-139. 

 Baker, F. C. 



'16 The Relation of Mollusks to Fish in Oneida Lake. Tech. Pub. no. 4, 



N. Y. State Coll. Forestry, pp. 1-366. 

 Baker, F. C. 



'18 The Productivity of Invertebrate Fish Food on the Bottom of Oneida 

 Lake, with Special Reference to Mollusks. Tech. Pub. no. 9, N. Y. 

 State Coll. Forestry, pp. 1-264. 

 Edmondson, C. H. 



'20 The Reformation of the Crystalline Style in Mya arenaria after Ex- 

 traction. Jour. Exp. Zool., Vol. 30, pp. 259-291. 

 Ege, R., and Krogh, A. 



'14 On the Relation between the Temperature and the Respiratory Ex- 

 change in Fishes. Int. Rev. ges. Hydrobiol., Bd. 7, pp. 48-55. 

 Evermann, B. W., and Clark, H. W. 



'17 The Unionidae of Lake Maxinkuckee. Proc. Ind. Acad. Sci., pp. 251- 

 285. 



