3TROPODA 



Buraul* lind^cjrl ] 



the slit shorter, than u-ual. Hightof shell 1- nun.; width of aperture 12 mm.; 



of same about *> mm.: \\nlthot uml>iliciH (',.:. nun.; \vi-lth of inner end of last volution 



about 4.7 mm. 



The form i- more globose and the umbilicus relatively smaller than in any of 

 tin- piv.v.img species of the genus. In both of these aspects it remimls one strongly 

 of B. sulcatina, of which it is probably a dwarfed descendant. 



Formation and loeatfly. The trpet arv from th<- uj.|--r part ..' th. Tn-nton jrrmip. n.-.-ir Bunrin, Ky. 

 A cut of the Interior, agreeing In ever/ renpect with tin- typo, wasfoutul in thr Ct<>n>Hi<itit:i U><1 i.r tin- 



.tain. Minnesota; another (tit. I'.'t i- fr""> '>!. Stnn". Kivr \ir<n\\>, at Mlnne- 

 apol. . small specimen, presumably of the uue specie*, occurred In tin- Ku-ispira Nil at Wykoff. 



Cbtlirtfan.-KO.Ulri 



Hl.-AXIA I.INMSI.KYl 



I. I.\\ !. HUH. M ami SS. 



Hdfcyi SAFFOUD, 1888, Oeol. of T.-nn., pi. . , t\^. 3a, b, ,1 and r. (:(c doubtful.) Not 

 described. 



11 30 mm. to 40 mm. in hight, the width of the aperture slightly less than 

 the greatest hight of shell; volutions about three, embracing less than a fourth of 

 the next within, rounded on the back, somewhat semi-circular in cross-section, 

 narrowly rounded beneath the middle line of the sides; umbilicus moderately steep, 

 of large size considering the rapid expansion of the volutions, its greatest width 

 equalling about one-third of the hight of the shell; aperture somewhat expanded in 

 the lower part, semi-elliptical in outline, the lateral angles narrowly rounded and 

 scarcely reflected, the center of the lower outline very slightly indented by the 

 preceding whorl; lower lip entire, thickened inwardly; upper or "outer lip thin, 

 the margin sweeping backward to form a broad shallow sinus, the center continuing 

 backward as a narrow slit, the latter having a length of at least 10 mm. in a speci- 

 men 38 mm. in bight. Surface coarsely lamellose, the lamella,*, which indicate the 

 margin of the aperture at previous stages, occurring at intervals on the back of the 

 last volution varying from less than 2 mm. to 4 mm. or more, the average being 

 about 3 mm. Usually the lamellae are crossed approximately at right angles by 

 more or less unequal and irregular ribs, seven to ten in the space of 5 mm., and 

 these again by tine lines of growth. Often the ribs are irregularly broken up and 

 sometimes they combine to form an obscure network reminding one of the surface 

 sculpture of It. i>uncti front Kmmons. (See pi. LXVII. fi^. }|>. Slit-band distinct, 

 -lightly concave, margined on each side by a sharply elevated, thin line; lunula* 

 somewhat unequal luit always clearly defined, rather crowded. 



This fine shell is readily <li-tingui*ht>l from all of the preceding species of the 

 genu- !'\ th*> i.ij-; : rvpansion of its wliorU. 



