COLUMELLA. 233 



tractor muscle at the apex. There is no appendix. The ovo- 

 testis is composed of a single mass of grape-like follicles, as in 

 Vertigo. The spermatheca has a rather long, slender duct. 



The jaw is wide, arcuate, composed of about 16 rhomboidal, 

 overlapping plates, not closely united, but not wholly uncon- 

 nected as in Punctum. 



The radula of C. edentula has about 42 teeth in a trans- 

 verse row. Centrals are tricuspid, side teeth bicuspid, the 

 cusps subequal, short; basal plates of all but the outermost 

 teeth are long, as in Punctum. There is no distinct differ- 

 entiation into lateral and marginal teeth. 



Type: C. edentula (Drap.). 



Columella is widely spread in the Palamrctic Region of 

 Europe and Asia, eastward to Japan, with four species in 

 North America, one as far south as Nicaragua. Two Hawaiian 

 species seem by conchological criteria to belong to the genus, 

 but until confirmed by anatomic examination their position 

 appears uncertain. The anatomy is known only in C. eden- 

 tula. 



C. edentula was formerly considered a Pupa or Vertigo. 

 Sterki (1896, 76) described the jaw and teeth, pointing out 

 similarity to Punctum. His description has been corroborated 

 by Professor Gwatkin (1897, 227, fig. 1) and by Miss Breen 

 (Hanna, 1911, 372), and the subject has been ably considered 

 by Hugh Watson (1923, 275, 279), who concludes that the 

 jaw of Columella "seems to differ from that of Vertigo in 

 that the oblong plates of which it is composed are less closely 

 united with one another." The genitalia were found by 

 Hanna and Watson to be much as in Vertigo and Truncatel- 

 lina. It differs from Vertigo, as Hanna writes, "in having 

 no teeth in the aperture of the shell, and the peristome thin 

 and without a callus deposit. Also the surface of the foot is 

 covered with a network of incised lines, which are not found 

 in any of the species of Vertigo examined by the writer. It 

 is allied to this genus by the animal lacking a lower pair of 

 tentacles and by the vas deferens being attached to the apex 

 of the penis, not down on its side as in Bifidaria [Gastrocopta] 

 or Pupoides. ' ' 



