PLATE XLVI. 



All the figures on this plate are magnified about twenty diameters. 



Pigs. 1 to 11. TETUADELI.A QUADKiLiBATA Hall and Whitfield, sp ('■'9 



1 to 3. Posterior, side, and dorsal views of a right valve. Middle third of the Trenton 

 shales, Minneapolis, Minn. 



4. Another right valve. Birdseye limestone, High Bridge, Kentucky. 



5. Inner side of a right valve. Minneapolis. 



6 to 8. Three views of a left valve, differing from the usual form in unimportant partic- 

 ulars. Minneapolis. 



9 to 11. Three views of a variety, agreeing with var. stmpZea; in wanting the po.''terior 

 marginal loculi. Trenton shales. Fountain, Minnesota. 



Figs. 12 to 14. Tbtbadbh,a ltjnatifeka Ulrich 680 



Three views of a left valve of a variety of this species. In other specimens that 

 were found with this one the antero-median ridge is more distinctly double. 

 (See cut, p. 680.) Galena shales, Cannon Falls, Minnesota. 



Figs. 15 and 16. Mookba ANGtrLABis, n. sp 682 



(See also plate xi.iii, fig. 89 ) 



Two views of a weather-worn valve, apparently of this species. Trenton shales. 

 Fountain, Minnesota. 



Figs, n and 18. Mooeea (?) pbbplbxa, n. sp 683 



Side and sectional views of the remarljable valve upon which this species is 

 founded. Trenton shales. Fountain, Minnesota. 



Figs. 19 to 22. Cbbatopsis chambeksi Miller, sp 676 



Side and ventral views of a left valve of the usual form. Upper third of the 



Trenton shales, St. Paul, Minnesota. 

 Inner side of a more elongate right valve, from the same locality. 

 Another right valve from the same locality, peculiar in having the small post- 

 median ridge divided. 



Figs. 23 to 25. BOLLIA tTNGULOIDBA, n. sp 669 



Three views of a left (?) valve. Galena shales. Cannon Falls, Minnesota. 



Figs. 26 to 29. Bollia ST:B.a;QUATA, n. sp 669 



26 and 27. End and side views of a valve of this species. Trenton shales. Fountain, Minn. 



28. A small valve from the same locality. 



29. Large and relatively high valve from the same position at Gannon Falls, Mirfn. 



Figs. 30 to 34. DiLOBBLLA TTPA, n. gen. et sp 673 



Figures of threa valves showing slight variations. Upper third of the Trenton 

 shales, St. Paul, Minnpsota. 



Figs. 35 to 38. DbEPANBLLA BILATEBALIS, n. sp 671 



A right (?) valve of the usual size and appearance. 

 Ventral and posterior views of a left valve. 

 Interior of a right valve. 

 Upper third of the Trenton shales, St. Paul, Minnesota. 



Figs. 39 and 40. Diceanblla bicoenis, n. gen. et. sp 665 



(See also plate xuv, fig. 26.) 



Side and posterior views of a nearly complete right valve. Middle third of the 

 Trenton shales, Minneapolis, Minn. 



Fig. 41. DiCKANBLLA SPINOSA, n. sp 665 



(See also plate xmv, fig. 23.) 



Posterior view of a left valve. 



Fig. 42. DiCKANBLLA (?) SIMPLEX, n. sp 666 



Ventral view of the valve figured on plate XLIV, flgs. 24 and 25. 



Figs. 43 to 46. Halliella labiosa, n. sp 656 



43 to 45. Anterior, dorsal, and left side views of an entire carapace. Galena shales near 

 Cannon Falls, Minnesota. 

 46. Somewhat weathered and relatively longer left valve: from the same locality. 



