Raymond : Gastropoda of the Chazy Formation. 193 



Point, New York, and the paratype is from the south end of Valcour 

 Island, New York. Both specimens are in the Carnegie Museum. 



Genus Liospira Ulrich and Scofield. 

 Liospira docens (Billings). 



Pleurotomaria docens Billings, 1859, Canadian Naturalist and Geologist, 



Vol. IV, p. 452, figs. 27-29. 

 Pleurotomaria docens Billings, 1863, Geology Canada, p. 132, fig. 63. 



Only one specimen of this shell is now known, and, though quite 

 well preserved, it does not serve to define the characters of the species 

 as fully as might be wished. 



The shell has the form, and, according to Billings, the closed umbili- 

 cus of Raphistoma, but it lacks the sigmoidally curved and interrupted 

 striae which characterize that genus. It possesses a true slit band, 

 and must therefore be placed in the Pleurotomariidae. 



In the absence of an umbilicus, and in the prolonged, conical shape 

 of the lower portion of the body whorl, the shell differs markedly 

 from the typical species of Liospira, yet there is no other genus in the 

 family to which it is more closely allied. The essential part of Bil- 

 lings' description follows. 



" Spire nearly flat; base sub-hemispherical; umbilicus closed; 

 whorls about four, with a distinct spiral band all around the outer 

 margin ; width, usually a little more than an inch and a half; height 

 about two-thirds of the width. 



" On the upper side the whorls in the center are gently convex and 

 elevated, so that the apex is about three lines higher than the outer 

 margin. As the whorls enlarge, they gradually lose the slight con- 

 vexity which they possess at the center, and become more and more 

 flattened, until at the aperture the last is quite flat or even a little con- 

 cave. The first whorl is very small, but the others somewhat rapidly 

 enlarge so that at the aperture the last one is full six lines wide, where 

 the whole width is eighteen lines. 



"The band forms the outer margin of the upper surface. At the 

 aperture it is one line wide, but it becomes gradually smaller, and at 

 the apex is reduced to a mere line. It is crossed by strong, backward 

 curving striae, and has a fine elevated line-like ridge on each side. 



" On the lower side the whorls are ventricose, and constitute a sub- 

 hemispherical or depressed conical base. At the aperture the outer 



