THE NAUTILUS. 



Vol.. XVI. DECEMBER, 19O2. No. 8. 



SURFACE SCULPTURE IN ANCYLUS. 



BY BRYANT WALKER. 



Owing to the simple character of tlie shell, which presents but few 

 of tlie salient specific features which enable the more specialized 

 groups to he readily determined, the North American Aiicyli, like 

 the Succineas, have received but scant attention from our collectors, 

 and great confusion exists in regard to the identification of nearly 

 all the described species. 



The species of the earlier authors were based almost wholly upon 

 the shape, contour of the slopes and position of the apex. The sur- 

 face sculpture was as a rule overlooked. With the exception of tl.e 

 few species characterized by radial ribs or incised lines, in only four 

 of tlie eastern American forms is the character of the surface men- 

 tioned at all in the original descriptions, and then only with reference 

 to the growth lines. 



Uourgiiignat, in 1853 (Journal de ConcJiyliologie, IV, p. G3), was 

 the first to point out the apical scar as a peculiarity ot ihe genus, and 

 Pilshry (NAUTILUS, IX, p. 13!>) is the only American author \\ho 

 has noticed its presence in any American species. It is present in 

 all of them, but is much less conspicuous in those species which group 

 around A. fuscus than in those of which A. ricularis is the leading 

 form. 



Pilshry also was the first (lac. dt.} to call attention to the fact 

 " that nearly all specimens are more or less coated with foreign mat- 

 ter, sometimes calcareous, but generally ferruginous (which ) must be 

 removed before the color and liner sculpture can be observed," and 

 to give a practical method for cleaning the shells. 



