22 THE NAUTILUS. 



perating shells, although of course in this particular case the 

 excess of CaC0 3 itself, may inhibit extended absorption of itself, 

 or this be prevented by the presence of other compounds. In 

 conclusion, I wish to express my obligation to Dr. A. E. 

 Ortmann, on whose material at the Carnegie Museum these 

 observations were made. 



BIBLIOGRAPHY. 



1. Hey, W. C. "Freshwater Shells in the Ouse and Foss." Journal Con- 

 chology, Vol. 3, no. 9, 1882. 



2. Shrubsole, G. W. " Erosion of Certain Freshwater Shells." Journal Con- 

 chology, Vol. 2, no. 3, 18. 



3. Beauchamp, W. " Eroded Shells." Conchol. Exchange, Vol. 1, p. 50, 

 1886. 



4. March, M. C. " Studies in Morphogenesis of Certain Pelcypods." 4a. 

 Preliminary Note on Variation of U. pictorum, U. tumidus, Anodonta cygnea." 

 Mem. and Proc. Manchester Lit. and Phil. Soc., 1910-11, p. 1-18. 



5. Cooper, J. E. " Note on Decollated Shells." Journal Conchol. Vol 13, 

 no. 1, 1910. 



6. Baker, F. C. " On some Variations of Cardium edule apparently corre- 

 lated to the conditions of Life." Phil. Trans. 1889. 



7. Rich, S. C. " An aberrant Form of U. complanatus, Dillwyn." Science, 

 N. S. Vol. XLII, no. 1086, 1915. 



8. Lewis, S. G. " Quality of Water in the Upper Ohio River Basin and at 

 Erie, Pa," Water Supply Paper, 161, U. S. Geol. Survey, 1906. 



9. Walker, Bryant. " Unione Fauna of the Great Lakes." NAUTILUS 27, 

 1913. 



10. Grier, N. M. "New Varieties of Naiades from L. Erie." NAUTILUS 32, 

 1918. 



A NEW ALASKAN CHITON. 



BY WILLIAM HEALEY CALL. 



SCHIZOPLAX MULTICOLOR n. Sp. 



Chiton depressed, broad, wider behind than in front, maroon 

 varied with white streaks, with a rather wide girdle, the surface 

 of which is covered with soft bristles like those of Mopalia mus- 

 cosa, among which are sparsely scattered, irregularly disposed, 

 longer translucent spicules; surface of the valves minutely uni- 

 formly reticulate under the lens, appearing smooth to the un- 

 aided eye; the mesial suture evident, the fifth valve widest, the 



