128 ORCULA. 



lamellae has gone further : the lower lamella is weak and not 

 rarely represented by a short, low little ridge far within, 

 occasionally wanting. As a rule the upper lamella is wanting ; 

 only seldom a small vestige remains. The smallest examples 

 of this form I have from the Heukuppe, 2009 meters, the 

 highest point of the Rax. Width 2.5 mm., length 5.6 to 5.7 

 mm. (fig. 10). 0. d. oreina is confined to the subalpine zone 

 of the highest elevations of the northern Dolomites and reaches 

 about to the tree limit, thus upward generally to 1600 meters, 

 at its lower limit gradually merging into the form edita. 



Orcula dolium pseudogularis a. J. Wagner (vol. 27, p. 

 11). Text-fig. 11, is a local form of the metamorphic Mesozoic 

 rocks of the Tiirkensturz, Gleissenfeld in the Pittental, lower 

 Austria. Wagner's measurements are erroneous. The aver- 

 age length is 7.2 mm. single specimens up to 8 mm., none over 

 3 mm. wide. The medium breadth is 2.7 mm., the slenderest 

 2.6 mm., only a few reaching 3 mm. wide. 



Orcula dolium gracilior St. Zim. Text-fig. 12. 



The dimensions of this form are strikingly constant, its 

 medium being for length 6.3 to 6.8 mm., for width 2.8 to 3 

 mm. ; the diameter being that of edita, but the length some- 

 what less. A conspicuous difference from edita is in the 

 eolumellar lamellae which wholly resemble those of typical 

 dolium and are even more regular than in that, strong and 

 equally developed. Thus out of 40 from one place in the 

 Adlitzgraben on the Semmerling, only three have the upper 

 lamella weaker than the lower (fig. 12). It is a miniature of 

 dolium. It inhabits a restricted district of the eastern border 

 of the Alps, from the slopes of the Sonnwendstein and the 

 Semmering in lower Austria in a northwestern direction about 

 to Gloggnitz. 



Ziramermann is disposed to view pseudogularis and gracilior 

 as modified subalpine enclaves of 0. d. edita. 



Orcula dolium Drap. intermediate with gularis Rssm. 

 (0. gularis pseudodolium A. J. Wagner, vol. 27, p. 14). 

 Text-figs. 13, 14, 15. 



