ri.vn; i.\\ 



fig*, i A U. ami - 1006 



1 and 2 Raul and dorsal views of a 1-1 of the interior. Trenton group 



uplra bed), near Cannon Falls, M 



:i A test!' ini| from ' i t-<l of tli-' Klark K Ivor group, at 



Chatfleld, Minnesota As utual UK- surface markings are very Imperfectly 

 preserved. 



4 Small portion showing weathered surface markings, and profile outline of last 



whorl, .2, as shown in a specimen from Goodhue county !,! It was foutnl 

 In tip- rtenmloiita bed. 



Figs. Sand 6 CLATHBOATIKA SUBCONICA Hall 1000 



(too !> pUt. l.M 



5 Surface markings and proille outline of last whorl of a small but well preserved 



exa linn-tone. Tenne 



6 Similar figures lak<>n from :i young examjii<- found In the upper nn-mber of 



tin- MIIIH-S i;i\.-r group near Lebanon, Tennessee. In tin- -p ,-iiin-n the 

 , line* on the upper slope appear not to crocs the lines of growth. 



I 7 PUKI \ STRIATA Ulrlch . 1011 



Apertura) view of an Imperfect -IN -eimcri. -howlng the comparatively low spire 

 and coarse rib-like line* of growth which are characteristic of the species. 

 Richmond group, Ifutli-r county, Ohla 



Figs. 8 to 10 PLcrnoariKA SEMKLE Hall 1010 



8 View of an Incomplete example, preserving the surface markings. Utlca group, 



near Graf. Iowa. 



9 1'ortion <>r List whorl of same magnified. 



10 A cast of the Interior from the same locality, doubtfully referred to this species. 

 Geological and Natural Historv Survey of Minnesota. Museum li.-gi-t.-r No. 

 7334. In another cast the peripheral band Is nut Hat but almost as distinctly 

 "ticave as on the exterior of the shell. 



Fig*. Hand 12 

 Fits. 13 and 14 



Figs. 15 to 17 

 15 



16 and 17 



Figs. 18 to 96 

 18 and 19 



H 



i. 



:> > _*. 

 30 to 30 



SKKI.YA MI-NI>I-I.A I'lrlch 1012 



Two specimens of this species, the second somewhat shortened by pressure, 

 from the lower half of the Lorraine group at Newport, Kentucky. 



!|..|:M"itMA TRENTONEN8IS U. and 8 1017 



Two views of a rather small but almost perfect cast of the Interior, retaining, 

 as shown in tin. 13. remains of the regular surface markings. Fuslsplra bed f 

 the Trenton group. Wykoff. Minnesota. 



HORXOTOMA BKLLIOINCTA Hall 



An average cast of the Interior of this species, showing that It baa a wider apical 

 angle and more depressed and. therefore, relatively more numerous volution- 

 than //. trtntoneiiti*. Clltambonltei bed of the Trenton group, Qoodhue county. 

 Minnesota. 



Another specimen, from the same locality, retaining some of the surface 

 markings. The greater part of the last whorl Is broken away so as to expose 

 (see tig. 17) the Oiling of the small umbilical perforation. 



Hi IIIMIITOMA OKACttis Hall, and varieties 



Two views, natural size and a portion magnified, if a specimen of what we regard 

 as the typical form of this species. Utlca group, Graf, Iowa. Geological and 

 Natural I of Minnesota, Museum Register No. 7337. 



Three specimens selected from a number which were found In association with 

 var. muUirolri* in 'iiotid group near Spring Valley, Minnesota. The 



flrst Is very much like the var. tmguttata (Hall), the second Is a typical yracili*. 

 the third has unusually angular whorls and may be compared with 

 var. ivbanyulatn. See flgs. 42 and 43. 



Three figures of the var. nMaxa. The Drat U made up of the apical portion of 

 one specimen and the lower whorls of another, ami shows the relatively loose 

 colling of the whorls and the resulting olill<iulty of the sutures which distin- 

 guishes this variety from the others. The second figure represents the two 

 lower whorls of same, y2, while the third figure represents a portion of another 

 it also x2. I i.th of these figures snow that the band Is considerably 

 wider than in otln-r forms of the species. Trenton formation. Lincoln county. 

 Missouri. 



F<>ur figuresof the var. muttirofou. The first represents an almost entin- -hell, the 

 second and third opposite views of a less perfect example, the fourth an unu-u 

 ally small specimen. This variety Is <: lied by it* more numerous 



wh h iii< ind group, near Spr .Minnesota. 



Seven flw i'-n- whi'-h \v.- \\.\ ,-d with the varlet> of tins 



species which Hall described In 1847 as JftcroUxmia anguMata. Pig. 30 represents 

 a weathered example from the Stones River group, at 11 _. Kentucky. 



The original of fig. 31 Is a gutta percha Impression of a natural mould In rock 

 from .1- -i at Belolt, Wisconsin: that of fig. 32 Is from tt- 



Phylloportna bed of the Black River group near Cannon Falls, Minnesota. Fig. 

 J3 shows two whorls, x2, of a Black River limestone specimen from Tennessee. 

 Figs. 34 and 36 represent opposite views of two specimens from the Utlca group 

 at Newport, Kentucky, and flg. 36 the lower part of a third specimen from Ibis 

 locality. The last shows the form of the apertural notch. 



1017 



1014 



