PLATE XLIII. 



Unless otherwise stated all the figures are magnified about twenty diameters. 



Page. 



Figs. 1 to 3. LeEEKDITELLA CANALIS, n. sp 637 



Anterior lateral and ventral vle^s of a left valve. Lower Trenton limestone, ~ 



Minneapolis, Minnesota. 



Pigs. 4 to 6. LePERDITELLA PEKSIMILIS, n. sp 637 



The right side, anterior and ventral views of a rather small specimen. Middle 

 third of the Trenton shales, Minneapolis, Minn. 



Figs. 7 to 9. LePBBDITELLA MACKA, n. sp ' 638 



The right side, anterior and ventral views of the specimen described, showing 

 the remarkably compressed character of the anterior part. Middle third of 

 the Trenton shales, Minneapolis, Minn. 



Figs. 10 to 14. Lepbrditia fabttlites Conrad 634 



10. Cast of the interior of the larger (right) valve, showing impressions of the two 

 sets of internal papillae along the ventral margin, x 2. Lower Trenton lime- 

 stone, Minneapolis, Minii. 

 11 to 14. Dorsal, ventral, right side, and posterior views, x 2, of an excellently preserved 

 testiferous carapace, from the same formation and locality. The "eye tu- 

 bercle" is unusually distinct. 



Figs. 15 to 17. Aparchites ellipticus, n. sp 644 



15 and 17. Posterior and ventral views of an entire carapace. Lower third of the Trenton 

 shales, Minneapolis. 

 16. ' The right side of another specimen from the same locality. 



Figs. 18 to 20. Apakchites mintjtissimus, var. trentonensis 646 



18. A,small right- valve from the Trenton shales, near Fountain, Minnesota. 

 19 and 20. Lateral and ventral views of a larger valve from the Galena shales, near Cannon 

 Falls, Minnesota. 



Figs. 21 to 25. Cytherella? bugosa Jones, and var. abota, n var 686 



21 to 24. Lateral and edge views of two valves of this species, from the Galena shales, near' 

 , Cannon Falls, Minn. 



25. A valve of the var. abcta, from the middle beds of the Galena of Goodhue county, 



Minnesota. The generic position of this species is doubtful, and, to facilitate 

 comparison with Bythocypris and allied genera, this specimen has been drawn 

 with theconvex margin uppermost. 



Figs. 26 to 29. Peimitiella simulans, n. sp 648 



26. Left valve somewhat doubtfully referred to this species. 



27 to 29. Three views of a typical right valve. Both specimens from the Trenton shales, 

 near Fountain, Minnesoia. 



Figs. 30 to 34. Macronotella SCOFIBLDI, n. gen. et sp 684 



30 to 32. Three views of a valve from the lower Trenton limestone at Cannon Falls, Minn. 

 33 and 34. Two views of a long variety from the Birdseye limestone at High Bridge, 

 Kentucky. 



Figs. 35 and 36. Aparchites ? arrectus, n. sp 646 



Two views of a left (?) valve. Upper third of the Trenton shales, St. Paul, Minn . 



Figs. 37 and 38. Aparchites chatfibldensis, n. sp 646 



Two views of a left valve the surface of which is somewhat abraded. Middle 

 third of the Trentoji shales, Chatfleld, Minnesota. 



Figs. 39 to 41. SCHMiDTBLLA iNCOMPTA, var. siTB^QUALis, n. sp. et var 642 



(See also plate xlv, figs. 27, 33 and 33.) 



Three views of a right valve. Galena shales, near Cannon Falls, Minnesota. 



Figs. 42 to 44. SCHMIDTELLA CRASSIMARGINATA Ulrich 640 



Exterior of a right valve, x 10, showing the broad border. Lower Trenton lime- 

 stone. Mineral Point, Wisconsin. 

 Ventral and posterior views of same. 



Figs. 45 to 47. SCHMIDTBLLA AFFINIS, n. Sp 641 



Anterior and side views of a right valve. Galena shales, near Cannon Falls, 

 Minnesota. 

 47. Interior of the largest right valve seen. The specimen is slightly distorted so 

 that the hinge is bent inwardly. 



[OVER.] 



