GASTROPODA. 



Motion, nearly equ;il. In internal casts of old shells the peripheral or central 

 angle is sharp :m<l prominent on the lower turns only, while it is nearly obsolete on 

 the upper ones; l.i-t whorl exhibiting a well-marked lower angle between which 

 and the peripheral curina there is a broad concave band, while the under side, 

 between the lower angle and the relatively large and abrupt umbilicus, is only 

 -liirhtly convex: in the mi<l<lle of the basal space the cast exhibits an obscurely 

 defined line; upper slope gently concave or flat, except near the suture where the 

 internal ca>t i< slight, \. The matrix shows that there was a thin upper 



..i on the shell. Surface markings but faintly indicated \>y the specimens at 

 hand. Imt U tain that they curved backward strongly as in //. pernngulntn, 



while it is probable that they agreed in other respects also with those marking that 

 species. 



The umbilicus is larger in this species than in any of genus previously described. 

 In other respects it resembles L. pulchella very closely, though a much larger shell. 

 /,. tillmortnsis, though considerably smaller and without an umbilicus, will strike 

 the ordinary observer as even more like it. Rut if good specimens can be compared 

 it will be noticed that the lines of growth on the concave band beneath the 



pheral angle of L. fillmoretuis are but little oblique and nearly straight instead 

 of strongly curved backward in short that that shell belongs near L. bicincta, while 

 L. perforate is one of the group of which L. perangulata is typical. 



We have before us the original type used by Meek and Worthen. After clearing 

 it of the matrix we found that it has at least one more whorl than stated by them, 

 and that the apical angle instead of being 55 is not more than 50. The last whorl 

 of the specimen i- cm-died in such a manner that the angle has been increased at 

 least 5 beyond the normal. An examination of the matrix proved further that the 

 shell really has an upper carina. Finally, it is clear that the umbilicus was not 

 filled, as they supposed, by the columella. That it was not is conclusively shown by 

 the core of limestone occupying all the cavity save a narrow space between it and 

 the castof the interior of the whorls which represents the space originally occupied 

 by the walls of the shell. 



Formation an.l locality. Trenton proup. Jo Davlens and Carmll counties. Illinois. We refer her,' 

 two small casts from the Fu*lplra bed near Fountain, Minnesota. 



. Illinois SUte Museum: I 



I-KKI.AMKI.I.O-A. n p. (I Irich.) 



:OS. H.M1SL 



Hight 13 mm.; greatest width about 10 mm.; apical angle 05 . Spire subconical, 

 volutions about five, angular: upper side first gently convex and then slightly 



