THE NAUTILUS. 105 



Presidential Address The Armature of Land Mollusca. By 

 G. K. Gude, pp. 52-73. 



Note on Xylophaga praestans Smith. By J. R. LeB. Tomlin, 

 p. 73. 



Concerning Edenttellina. By Charles Hedley, pp. 74-76. 

 E. corallensis n. sp. , p. 76, figs. 6-8. 



Nomenclatorial Notes Relating to British Non-marine Mol- 

 lusca. By A. S. Kennard and B. B. Woodward, pp. 77-90. 



The Anatomy of two species of Helicarion from Tropical 

 Africa. By Hugh Watson, pp. 91-118, pis. 3 & 4. H. crypto- 

 phallus n. sp. , p. 97, pi. 4. 



Mitra burnupiana n. sp., from South Africa. By Rev. A. 

 H. Cooke, p. 114. 



Note on the dates of publication of the earlier parts of Cap- 

 tain Thomas Brown's Illustrations of the Conchology of Great 

 Britain and Ireland. 2nd edition. By Alexander Reynell, 

 p. 116. 



CORRELATION OF SHAPE AND STATION IN FRESHWATER MUS- 

 SELS (Naiades). By A. E. Ortmann. (Proc. Amer. Phil. Soc., 

 1920, Vol. 19, pp. 269-312.) The author has ascertained 

 "that the more obese (swollen) form is found farther 

 down in the larger rivers, and passes gradually, in the upstream 

 direction, into a less obese (compressed) form in the head- 

 waters; with the decrease in obesity often an increase in size 

 (length) is correlated; a few shells which have in the large 

 rivers a peculiar sculpture of large tubercles, lose these tubercles 

 in the headwaters." The observations were made in the head- 

 waters of the Ohio and Tennessee Rivers. 



VARIATION IN NACREOUS COLOR OF CERTAIN SPECIES OF NAIADES 

 INHABITING THE UPPER OHIO DRAINAGE AND THEIR CORRESPOND- 

 ING ONES IN LAKE ERIE. By N. M. Grier (Amer. Midland 

 Nat, 1920, pp, 211-243, Vols. 2-3 \ In a summary the author 

 says "In practically all the species dealt with a change in 

 nacreous color is observed going down stream from the head- 

 waters to the mouth. . . The shells of L. Erie have a greater 



