212 PROCEEDINGS OF THE ACADEMY OF [Mch., 
upon in the discussion of the composite nature of snail colonies (p. 226), 
since the conclusions reached from molluscan studies apply equally to 
communities of other comparatively sedentary animals. 
Throughout the preparation of this paper I have had the coépera- 
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FOOTHILLS ly, 
Sketch of Huachuca range, by J. H. Ferriss. 
tion of Mr. J. H. Ferriss. I would also gratefully acknowledge assist- 
ance lent by Dr. Wm. H. Dall, in the comparison of various species 
of Holospira, etc., with those described by him. 
The figures of shells were photographed and those of soft anatomy 
drawn by the author. 
