The Nautilus. 



^' 



Vol. XVI. 



DECEMBER, 1902. 



No. 8. 



SUEFACE SCULPTURE IN ANCYLUS. 



15 Y BRYANT WAI.KKR. 



Owinn^ to tlie simpl<^ cliai'iicter of" the shell, vvliicli jiresents but few 

 of" the salient specific features wliicli enable the more specialized 

 groups to lie readily determined, tiie North American Atici/h\ like 

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

 and great conlusion exists in regard to the identiHcatiou of nearly 

 all the described species. 



The spccii'S of the earlier authors were based almost wholly nprn 

 the shape, contour of the slopes and position of the ajtex. Tiie sur- 

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

 few species characterized l)y radial riiis or incised lines, in only four 

 of the eastern American forms is the character of the surface nien- 

 tioneil at all in the origiiuil descriptions, and then only with refeience 

 to the growth lines, 



Bourguignjit, in 1853 (Journal de Cunchyh'dJngie, IV, p. 03), was 

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

 Pilsbry (Naltii.us, IX, p. IB'.t) is the only American author who 

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

 all of them, but is much less cons])icuous in those species which group 

 around A. J use us than in those of which A. ricuhin's is the leading 

 form. 



Pilsbry also was the fiist {loc. dt.) to call attention to the fact 

 " th;it nearly all specimens are more or less coated with foreign mat- 

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

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

 to give a (iractical method lor cleaning the shells. 



