WEST AMERICAN PYRAMIDELLID MOLLUSKS. 137 



ments formino; nodules. The axial ribs pass only faintly over the 

 base, while the spiral sculpture remains quite prominent. 



Type. — Odostomia (Ohrysallida) forrita n. n. = CJirysallida communis 

 Carpenter; not Chemnitzia [= CJirysallida] communis C. B. Adams. 



KEY TO THE SPECIES OP THE SUBGENUS CHRYSALLIDA. 



All spiral cords between the sutures nodulose. 

 Sutures strongly channeled. 



Axial ribs always stronger than the spiral cords. 



Basal cords 5 reigeni, p. 138. 



Basal cords 6 inconspicua, p. 139. 



Basal cords 7 telescopium, p. 139. 



Basal cords 8 excelsa, p. 140. 



Basal cords 9 acrybia, p. 141. 



Basal cords 10 communis, p. 141. 



Basal cords 12. 



Outer lip of adult shell pinched in torrita, p. 142. 



Outer lip of adult shell not pinched in. 



Axial ribs of last whorl 16 licina, p. 143. 



Axial ribs of last whorl 22 talama, p. 143. 



Axial ribs not as strong as the spiral cords. 



Spiral cords 4 between the sutiu"es on the later whorls. 

 Shell slender, elongate-conic. 

 Basal cords 8. 



Diameter more than 1 mm cffusa, p. 144. 



Diameter less than 1 mm paupercula, p. 144. 



Basal cords 7 clathratula, p. 145. 



Basal cords 6. 



Adult shell 4.5 mm. long ritteri, p. 146. 



Adult shell 2.3 mm. long rinella, p. 146. 



Basal cords 5 eugena, p. 147. 



Shell ovate or broadly conic. 



Basal cords 4 trachis, p. 148. 



Basal cords 5. 



Shell large, adult 4.0 mm. long lucca, p. 148. 



Shell small, adult 2.3 mm. long Clementina, p. 149. 



Basal cords 6. 



Outer lip of adult shell decidedly pinched in. oomsca, p. ]50. 

 Outer lip of adult shell not pinched in. 



Whorls slopingly shouldered oldroydi, p. 150. 



WTiorls not shouldered. 



Axial ribs decidedly retractive nodosa, p. 151. 



Nodules round ovata, p. 152. 



Nodules oval cincta, p. 152. 



Basal cords 7 . 



Base of the last whorl strongly inflated loomisi, p. 153. 



Base of the last whorl somewhat excavated. 



Spaces between the spiral cords mere impressed lines. 



vicola, p. 153. 

 Spaces between the spiral cords broad, deep channels. 



astricta, p. 154. 



Basal cords 8 cooperi, p. 155. 



Basal cords 9 hipolitensis, p. 155. 



Spiral cords 5 between the sutures of thelater whorls, fopazona, p. 156. 

 Spiral cords 6 between the suturesof thelaterwhorls.proa:ima, p. 157. 



