Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Toto; “3s 
10 to 14. 
10. 
1l to 14. 
15 to 17. 
15 and 17. 
16. 
18 to 20. 
18. 
19 and 20. 
21 to 26. 
21 to 24. 
26 to 29. 
27 to 29. 
30 to 34. 
30 to 32. 
33 and 34. 
35 and 36. 
37 and 38. 
39 to 41. 
42 to 44. 
42. 
43 and 44. 
45 to 47. 
45 and 46. 
47, 
PLATE XLIII. 
Unless otherwise stated all the figures are magnified about twenty diameters, 
LEPERDITELLA CANALIS, 0. SDP........--...-.--- Romxcadss SAAC Hee SBR EEE On HORA a 
Anterior lateral and ventral views of a left valve. Lower Trenton limestone, 
Minneapolis, Minnesota. : 
TEPERD ITEM AD PERSUMUGIG HT 1SeS Pe icslocleisteleleleiels oi eloye «inv olofas eH atL AM ats cleishels sie =< Psie/-\- 
The right side, anterior and ventral views of a rather small specimen. Middle 
third of the Trenton shales, Minneapolis, Minn. 
PERER DEE TD AP MAC HAUNT SDbermencie sive ceetot clic se aslo «le et es a Poke 
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, 
DIP MRD LET AGATE DIS, OO MCA C ereevctel taper ctatar=(atetessiovelernicieiclelelaiieierercleieness ataleratefertrebelejerar severe 
Cast of the interior of the larger (right) valve, showing impressions of the two 
sets of internal papille along the ventral margin, x 2. Lower Trenton lime- 
stone, Minneapolis, Minn. 
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. 
APARCHITES ELLIPTIOUS, MN. SD... .. 2+ +. esse ere ee teens eee etter este ee een teens 
Posterior and ventral views of an entire carapace. Lower third of the Trenton 
shales, Minneapolis. 
The right side of another specimen from the same locality. 
APARCHITES MINUTISSIMUS, Var. TRENTONENSIS. .........00.csceccee sees ceceerece 
A small right valve from the Trenton shales, near Fountain, Minnesota. 
Lateral and ventral views of a larger valve from the Galena shales, near Cannon 
Falls, Minnesota. 
CXMPHEREDLA RUGOSArs OWES: ANG, Valw A OMA STU VUE ctstelelexeiniatalelsi-1a/sieinlcrefsleletelelaye else 
Lateral and edge views of two valves of this species, from the Galena shales, near 
Cannon Falls, Minn. 
A valve of the var. ARCTA, 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 the convex margin uppermost. 
(PRIMTTEBTISA\ SEMUD ANS os SP iis varessiciodbies blaaloliacied <leleiieeieets che Lum te ec gee eile and 
Left valve somewhat doubtfully referred to this species. 
Three views of a typical right valve. Both specimens from the Trenton shales, 
near Fountain, Minnesoia. 
MAGRONODEDEASSOORLHEDE, MO eMs CISD iaetee Us mriele islet alels Aelelaleeielale »'eleidialelecisie ini ele 
Three views of a valve from the lower Trenton limestone at Cannon Falls, Minn. 
Two views of a long variety from the Birdseye limestone at High Bridge, 
Kentucky. 
APPAR CHIDESS ARE IU Syl euS pte creieyatels lel aielavelotenelsietenvereh ties) etol etabetapel ahaa. s/elars at</ohellelecleisiepe re 
Two views of a left (?) valve. Upper third of the Trenton shales, St. Paul, Minn. 
APLAR CHIMPES 26 HATMTETD GNSS. Ist SP st <tsce stetelate cca ietehasiae «cle ete oleleleisielelete 01 e1 cierere siclsis «1s 
Two views of a left valve the surface of which is somewhat abraded. Middle 
third of the Trenton shales, Chatfield, Minnesota. 
SCHMIDTELLA INCOMPTA, Var. SUBZQUALIS, D. Sp. Ct Var... .. 0.0... ee cece eee eee ee 
(See also plate xv, figs. 27, 32 and 33.) 
Three views of a right valve. Galena shales, near Cannon Falls, Minnesota. 
SCHMID TENE AL CRASSIMAUR GIN-ATAC YU) IPICHH ater dstec sale sais aeistelt/eiaisleteleie)sie lee > wislele sielei elas 
Exterior of a right valve, x 10, showing the broad border. Lower Trenton lime- 
stone, Mineral Point, Wisconsin. 
Ventral and posterior views of same. 
SCHMIDTEELAY AMBINIS: MejS Papers syecisielelelsiare elavarc e Malsmesicrelaiels os la) stale oversys Slcse 0) sisielajajs.e'viere 
Anterior and side views of a right valve. Galena shales, near Cannon Falls, 
Minnesota. = 
Interior of the largest right valve seen. The specimen is slightly distorted so 
that the hinge is bent inwardly. 
[OVER.] 
638 
634 
644 
646 
686 
648 
684 
646 
646 
640 
641 
