Bryant Walke;r 



Subgenus WALKEROLA Hannibal. 

 Shell as in Lan.v, but thinner and more depressed. 



Fig- 52 



Fig- 54 



Fig- 53 

 Type: Imux klaiiiathensis Hann., fig. 52. Radula, fig. 53. 



Genus FISHEROLA Hannibal, 1912. 



Shell rounded-ovate, somewhat broader anteriorly, 

 depressed-conic, finely concentrically striate, apex 

 small, indistinct, subterminal, but not inclined. Anat- 

 omy unknown. 



Type : Pishcrola lancides Hann., fig. 54. 



Subfamily FERRISSHNiE Walker, 1917. 



Shell small, thin, broadly ovate to oblong; apex more or less posterior 

 and eccentric, apex (in North American species) smooth or radially striate, 

 Animal having the jaw segmented in plates. Radula with a bicuspid central, 

 laterals obliquely reflected with from two to five small cusps, arranged like 

 the teeth of a comb, marginals also comb-like, cusps not (usually) extending 

 to the basal line. 



Key to the genera of Perrissiince. 



Shell never septate Ferrissia. 



Shell in maturity septate Giindlachia. 



Genus FERRISSIA Walker, 1903. 



Shell ovate to oblong, conic, more or less elevated, apex excentric and 

 posterior, radially striate or smooth. 

 Animal as in the subfamily. 



