PLATE I. \\VII. 



PA OK. 

 Flgi. 1 to 8 Tiu HMNKMA t MIMI.U A TIM Hall ................................................ .. 1047 



1 I nder lde of a cast of th.- iiit.-rinr, Madun-a U-d, Treoton group, Stewartsvllle, 



Minnesota. 



2 Lateral view of another cast: from the tame horl on at Hader. Minnesota. 



3 Outta percha cast of the exterior, the ]<>wer part of the figure restored; fnnu tin- 



same horizon near Galena, . Illinois. The mil-fare marking*. excepting 



occasionally on the base, are always fine and generally obscure In i In- Trrni<>n 



variety. 

 4 and 5 Front and basal vlews.of an excellent, though rather small, lllclfle<l specimen of 



tin- variety canadenrit. Black River or Stones River irroup. Pauiiuette's 



Rapids, Ottawa river. Canada. 

 6 Small portion of last whorl of same, magnified somewhat more than two 



diameters, showing the character and direction of the surface markings 



between the upper and lower carlne. 

 7 and 8 Basal and lateral views of a large cast of the Interior of a Stones River group 



variety from middle Tennessee. The whorls spread more rapidly than t 



should In T. wmbtiicatum but otherwise, especially In the direction of the lines of 



growth across the vertical face of the whorls, the agreement with this specie* Is 



very close. ThU form may be distinguished as var. latum. 



Fig*. 9 to 12 TKOCIIOHBHA HKACHI? Whltfleld ................................................. 1048 



9 Outta percha Impression of a natural mold of the upper side, showing surface 



marking*. On the vertical peripheral band the lines of growth lean backward 



about aa In fig. SI of this plate, not forward is In T. umbiticaium. Stones River 



group, Minneapolis, Minnesota. 



10 Castor the Interior from the same horizon at Janesvllle, Wisconsin, agreeing very 



well with WhltQeld's figure of bis T. beaehi. 

 1 1 ical section of the same species from Dlzon, Illinois. 



12 s.-rii,,n of last whorl of fig. 10. 



Figs. 13 to 18 TROCIIONKMA FRAOIIJI U. and S ................................................... 1050 



13 Lateral view of a cast of the Interior. Clltambonltes bed of the Trenton group, 



Cannon Falls, Minnesota. 



14 to 16 Three views of another cast; from Carroll county, Illinois. Like the other, this 

 specimen shows the remarkable sharpness, considering that It Is a cast, of the 

 angles, and the narrowness of the sutural groove when compared with T. 



Figs. 17 and 18 TROCIIONKMA ECCK Hrlch ............................................. . 1010 



Apertural and basal views of the best of three specimens from the upper division 

 ("Glade limestone") of the Stones River group near Lebanon, Tennessee. We 

 would point out that the lines of growth lean forward on the peripheral band 

 about as in T. umlnlieatum and that the present species la distinguished from 

 that by the eccentricity of the umbilical ridge chiefly. 



Figs. 19 to 22 TBOCBONKMA RCOOSUIC U. and S ............. 1049 



19 Outta percha Impression showing part of the periphery and und.-r -id.-. Stonea 



River group, Minneapolis, Minnesota. 

 30 and 21 Lateral and basal views of a cast of the Interior from the same locality. 



22 Upper side of a small specimen which, though somewhat abraded, still retains 

 some of the strong lines of growth; also from the Vanuxemla bed at Minne- 

 apolis, Minnesota. 



Figs. 23 to 25 TKX HOXEMA MADISOMKNSK Dlrich IO.M 



Three views of the type of this species. The absence of a basal angulstUm dis- 

 tinguishes It from all of the preceding forms. Richmond group, Madison, Indiana. 



