116 THE NAUTILUS. 
The figures on Pl. II] are from camera-lucida drawings all 
magnified 10 diameters. The shells were selected for size only, 
that is as near the same size as possible from material at hand, 
and from localities as near together as I had them in my collec- 
tion. Figs. 13 to 16 are large shells of each species. 
1—lamellidens Thunderhead, Gt, 
Smoky Mts... .... . . . Diam. 2.70 mm., Umbilicus .29 mana ct 
2—multidentata Oakdale, Morgan Co., t 
Tents het Had Mees eee ee SM LAH A aks: CO RS eaneceh 
3—lamellidens Anderson, Franklin } 
Gos) Deni ret ier fil or eee Orme ft se 
4—multidentata Sherwood, Franklin j 
Co), Tent. elie, ci iota Deira One Heplls), GC fe sean 
5—lamellidens Banners Elk, Wautauga 7} 
Bo Ge Ry Pd Tear aetna Tg apna tye Voie manger 
6—multidentata Cranberry, Mitchell r 
Cari Mice sw they Sat) Pe lea «46 J 
7—lamellidens Litchfield, N.Y... ‘' 2.40 “* us fy 3 Tee: 4 
8—multidentata Litchfield, N.Y... ‘ 2.53 %& oe AG pits 
9—lamellidens Deering, N.H. ... “ 2.13 & a sO Maes \ 
10—multidentata Hoosic, N.Y... . “ 2.53 “ o. AG re 
11—lamellidens Norway, Me... . . ‘' 2.08 ‘¢ f Sasi te \ 
12—multidentata Quebec, Can. . .. “ 2.70 % a Pas ie 
13—lamellidens No. 1, large shell . . ‘* 3.90 ¢ u vAG wrt 
14—multidentata Stevenson, Ala,,large ‘‘ 3.11 ‘¢ ae ane) oe 
15—Jlamellidens No, 1 same size as No, } 
WANT tees vet ho ar Onl Soke Mae eele co ney\ a Sere Metres e Net ans HS S310 2 
16—multidentata largest Quebec . 2... ‘4 = 3.07 a sean 
17—lamellidens No. 1 same size as 7, 9 
BO DT eye ob ay talip Wa lve) pealdulinas Be ee SRE q woot eee 
18—damellidens No. 1 same size as 7, 9 
Bm ED ies iors wip apts - Shieh Maat ORT a Pe uf bao) ae 
From the measurements given above it will be seen that in 
shells of approximately the same diameter the umbilicus in 
lamellidens is about three-fifths of the diameter of that of multi- 
dentata, the single marked exception being Nos. 3 and 4. 
In figures 18, 14, 15 and 16, mature shells, it will be noticed 
that in multidentata the umbilicus widens rapidly in the last 
whorl while in lamellidens it does not. This can also be seen 
in the other figures, but it is not so pronounced. 
