1911.] NATURAL SCIENCES OF PHILADELPHIA. 195 



palatal fold distinct. The larger ones from this place are typical in 

 shape; the smaller are shorter than syngenes from any other locality 

 in our series. 



Fig. 7. — Pupilla syngenes Pils. Spectacle Cove, near Bass Trail. Lengths 3.8, 



3.5 and 3.2 mm. 



Along the upper slope of the Bass or Mystic Spring Trail, Station 2, 

 there is an extensive colony of syngenid forms. We found them most 

 abundant in the humus, among low brushwood, about 200 feet below 

 the rim. Two forms occur here together, a dextral form, P. s. dextro- 

 versa, and a sinistral, P. s. avus, described below, in about equal 

 numbers, 272 of the former and 256 of the latter in the lot collected. 



The P. s. dextroversa are typical in shape, but larger than the types ; 

 the crest is wide and rather far from the lip-edge; a lower palatal 

 tooth is developed. Specimens measure: 



Length 4.5, diam. 1.8 mm., whorls 10. 

 3.7, " 1.8 " " 9. 



Fig. 8. — Pupilla syngenes form dextroversa P. and V. Bass Trail, about 200 feet 

 below the rim. Lengths 4.5 and 3.75 mm. 



The last is the smallest adult seen from this place; most examples 

 are over 4 mm. long. Specimens of this lot are figured, fig. 8. 



