176 PUPILLA, EUROPE. 



generally been called var. bigranata Rossm., but that appears 

 to be a special Central European form considered a separate 

 species by some authors. I do not know that masclanjana 

 ever occurs in pure colonies; it is associated with the pre- 

 ceding. 



4. Var. tridentata, Jeffreys has three teeth, one on the colu- 

 mella being added. Recent naturalists do not appear to have 

 noticed it, and it is not to be found in the Jeffreys collection. 

 However, it seems to be what has been called var. glis Wes- 

 terlund. 



This is a case where three forms have been initiated by the 

 loss of teeth by successive mutations; probably these muta- 

 tions have time and again occurred independently. They 

 cannot properly be ranked as subspecies, but rather as muta- 

 tions. Other mutations have the shell white or reversed, long 

 or short ; these are independent of tooth mutations. 



Other named tooth-mutations follow below, the original 

 accounts being given in all cases. 



Draparnaud in the Tableau, 1801, denned Pupa marginata 

 thus: "Coq. ouverture 1-plissee; peristome garni exterieure- 

 inent d'un bourrelet blanc. Long. 3 mill., diam. 2 in. 6 tours." 

 In the H'istoire, 1806, he enlarged the definition to include 

 specimens with a lower-palatal fold ; yet this later description 

 apparently included some shells we would not now include in 

 muscorwm, such as those having "une dent ou lame qui se 

 prolonge en tournant dans 1'interieur de la coquille." It is 

 evident that marginata can be properly used only for the 

 form usually termed unidentata, This is what Draparnaud 

 first described, and later figured. 



Mut, lidentata C. Pfr. was evidently an abnormal shell, 

 having two blunt denticles standing close together on the 

 parietal wall. 



Mut. tridentata Jeffr. A remarkable variety, the arrange- 

 ment of the teeth being the same as in P. tridentata [ ? tripli- 

 cata]. Between Bex and St. Maurice, Switzerland (Pupa 

 muscorum var. tridentata Jeffreys, Ann. Mag. N. H. (2), xv, 

 1855, p. 22). 



Mut. masclaryana Paladilhe. PI. 20, figs. 16, 17. Shell 



