PLATE LXXV1IT. 



PAGE. 



Figs. 1 to 9 TROCHONEMA BELOITENSE Whitfleld 1048 



1 Dorsal side of a cast of the interior, from Beloit, Wisconsin 



2 and 3 Umbilical and dorsal views of a well marked specimen of the form of the species 

 prevailing at Dixon, Illinois. Excepting the umbilical region, which gives an 

 idea of the thickness of the shell, the specimen is a cast of the interior. 



4 to 6 Three views of a large example, retaining most of the shell, from Mineral Point, 

 Wisconsin. 



7 Gutta percha impression of a natural mould of the exterior, from Beloit, Wis- 



consin. 



8 Dorsal side of an interior cast of the Minnesota form of the species, having the 



last whorl partly free; Minneapolis. 



9 Under side of a similar specimen from the same locality. 



Figs. 10 to 13 TROCHONEMA VAGRANS U. and S 1049 



(See also plate LXXVII, fig. 46.) 



10 and 11 Basal and lateral views of a cast of the interior, from Minneapolis. 

 12 and 13 Similar views of a nearly perfect cast from the same locality. Survey collection, 

 Museum Register No. 6865 



Figs. 14 to 16 GYRONEMA LIRATUM U. and S 1056 



Three views of the specimen upon which this species is founded. While the 

 greater part is preserved as a cast of the interior, a portion, as shown in flg. 14, 

 is of the exterior. Beloit, Wisconsin. 



Figs. 17 and 18 GYRONEMA SEMICARINATUM Salter sp 1055 



Dorsal views, natural size and x2, of a specimen retaining the shell; near Cannon 



Falls, Minnesota. 

 Figs. 19 to 21 GYRONEMA PULCHELL(TM U. and S : 1054 



19 Dorsal view of a small but nearly perfect example; Chatfleid, Minnesota. 



20 Portion of same x5 to show extremely fine lines of growth. 



21 Apertural view of a larger and excellently preserved specimen; Minneapolis. 



Geological and Natural History Survey of Minnesota, Museum Register No. 

 6854. 

 Figs. 22 to 25 GYRONEMA DUPLICATUM U. and S 1055 



22 Side view of a specimen which retains some of the shell and has a higher spire 



than usual; Dixon, Illinois. 



23 and 24 Apertural and dorsal views of a large and almost entire cast of the interior 

 belonging to the collection of the University of Wisconsin: Beloit, Wisconsin. 

 25 The lower whorl of a cast of the exterior from the same collection and locality. 



Fig. 26 CYCLONEMA (? GYRONEMA) PR.ECIPTUM, n. sp. (Ulrich.) 



Dorsal view of an average example of this species; Stones River group, Murfrees- 

 boro, Tennessee. It was through a species like this that Cydonema, was evolved 

 from Oyronema. The inner lip is relatively thicker, straighter, and more reflexed 

 than in species of Gyronema, but not excavated as it should be in a true 

 Cydonema. A minute umbilicus is often present. This species is referred to 

 but not named in the fifth paragraph on page 1046. 

 Figs. 27 and 28 CYCLONEMA VARICOSUM Hall 1060 



27 Apertural view of a specimen from the upper part of the Trenton group at Nash- 



ville, Tennessee. 



28 Dorsal view of a larger specimen, from Colby, Kentucky. The inner lip is nearly 



vertical and the carina; very strong in this species. 

 Figs. 29 and 30 CYCLONEMA MEDIALE Ulrich 1059 



29 Dorsal view of an average example of the typical form of this species; Covington, 



Kentucky. In another common variety the revolving carinae are less equal, 

 being more as in flg. 34 of this plate. 



30 Under side of another specimen from Covington. 



Figs. 31 and 32 CYCLONEMA INFLATUM Ulrich 1060 



Dorsal views of two specimens from Cincinnati, Ohio, showing rather extreme 

 conditions in the manner of growth. The apex in the first is entire. 



Figs. 33 and 34 CYCLONEMA PYRAMIDATUM James 1061 



Basal and dorsal views of a typical example of this species; from the vicinity of 



Morrow, Ohio. 

 Figs. 35 to 39 CYCLONEMA BILIX Conrad sp 1058 



35 Dorsal view of a rather large example of this species, from Versa'lles, Indiana. 



36 A similar view of a smaller specimen, from Waynesville, Ohio. 



37 A dorsal view of a third specimen, from Clarksville, Ohio. These three speci- 



mens are regarded as agreeing in every respect strictly with the original type of 

 the species. It is to be observed that the revolving carinte are not as strong as 

 in V. mediale, and the suture more abruptly impressed. 



38 and 39 Dorsal views of two specimens of the form which Miller proposed to distinguish 

 as variety conicum; from Versailles, Indiana. 



Figs. 40 to 42 CYCLONEMA BILIX var. FLUCTUATUM James 1059 



40 Dorsal view of a perfect specimen of this variety, from Versailles, Indiana, show- 

 ing the relatively line revolving lines, oblique folds and concave slopes of the 

 whorls which usually characterize this variety. 

 41 and 42 Two views, x5, of the apex of same. 

 Figs. 43 to 46 CYCLONEMA nuMEROsuM Ulrich 1061 



43 A large and strongly marked specimen of the Richmond group variety of this 



species; Waynesville, Ohio. Possibly this is an extreme variety of C. bilix, with 

 which It was found associated, rather than of the Lorraine group types of this 

 species. 



44 Apertural view of a large example of an abundant variety in the Lorraine group 



at Cincinnati. The whorls are more rounded and the "shoulder" less distinct 

 than in the typical form of the species. 



45 and 46 Dorsal and basal views of a typical example from Cincinnati. The shoulder at 

 the top of the whorls is often more pronounced. 



Fig. 47 CYCLONBMA SIMULANS Ulrich 1061 



Dorsal view of an average example of this species, showing the rather delicate 

 revolving lines growing more and more obsolete on the last volution; Cincin- 

 nati, Ohio. 

 Figs. 48 and 49 CYCLONEMA SUBL/EVK Ulrich 1062 



48 Dorsal view of a representative example; Covington. Kentucky. 



49 Similar view of a relatively higher specimen, from the same locality. 



