Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Fig. 
Figs. 
Tigs. 
Figs. 
Figs. 
PLATE XLV. 
Unless otherwise 1s stated, all the figures on this plate are magnified about twenty diameters, 
1 to 3 
2and 3. 
4 to 6. 
4and 5. 
i 00) = 9 
10 to 12. 
13 to 15. 
16 to 18. 
19 and 20. 
19. 
20 and 20a. 
21 to 23. 
24 to 26. 
28 to 30, 
31. 
27, 32—33. 
27. 
32 and 33. 
34 and 35. 
36 to 38. 
36 and 37. 
38. 
39 to 42, 
HURYCHILINA. VEN TROSA, TSP. OF VAL sme encecs cise tsietelstarsionsieciertmerctetaterter atten terete eater 
Left valve, imperfect at the extremities, yet preserving the essential characters 
of the species. Galena shales, Cannon Falls, Minnesota. 
Lateral and posterior views of a perfect right valve, from the same locality. 
HURYOHRILINA (2) SY MMETRICAG TaN) approve <teletevstalale etetenetarstsynictaiaanis late ake lalatotatnielsforcistelate vate 
(See also plate XLrv, figs. 5—7.) 
Side and end views of a valve. x 28, differing somewhat from the specimens 
figured on plate XLIV. Upper third of the Trenton shales, St. Paul, Minn. 
Longitudinal section of same. 
HURYCHILINA (7) SUBAIQU ADA, MIS ps siaesta siete iectietelsieteletele oie tenireieieieetetss ote alse ie iatiTe ee 
Side view of a left valve, with vertical and longitudinal sections of same. Upper 
third of the Trenton shales, St. Paul, Minnesota. 
APARCHITES 2FIMBRIATUS AUG bine. ars cla rates eters) wiera in) aieleietersderepsieisaetete eter emreliereaiesesinlerotere 
Side, ventral and posterior views of a right valve. Hudson River group, Spring 
Valley, Minnesota. 
LEPER DIT LGA TU MID AW OUTICI I sees ctcercyoet leon om cisbsceteredetetteiarciot ante eee ier tern atonts 
Side, dorsal,and posterior views of a typical right valve of this species, x 15, from 
the Birdseye limestone. at High Bridge, Kentucky. Introduced for comparison 
with Z. canalis and L. persimilis, figured on plate XLIII. 
APARCHITHS MILLEPUNCTATUS MU IriGlis tienes ioneetajeneletsjeverstalecen’are ete icicle ieee tece 
Ventral; anterior, and side views of aright valve. Surface punctation omitted 
except on the antero-dorsal fourth of fig. 18. Trenton shales, Fountain, Minn. 
TWEPERDITELGA DORSICORNISHU TICK: -cr sce sal icivie fel eelelsllemicie ere beet te cee eer eres 
A left valve, x 15. Hudson River group, Savannah, Lllinois. 
Outlines of same in dorsal and anterior views. 
APPAR CHELES <G ANDAR TAT ACm ULE] Chi seryereicte e's ralelerestarolny sverieretsisichs (ee oteieisteyetaeie suai eR iaers 
Posterior, side, and ventral views of a left valve. The minute surface granules 
are omitted except on a small space of fig. 22. Upper third of the Trenton 
shales. St. Paul, Minnesota. 
LUEPRRDITEDU A GHRMAIN A: (UILDLCI 1. vie ctelstclsivialc staloisis-nleieie lee cea Sh EEE 
Outlines of a left valve in anterior, side, and ventral views, x 15. Lower Tren- 
ton limestone, Mineral Point, Wisconsin. 
PRIMTIEE CA GETE LT MORENSIG,) Ets) hemi. steteelelateieieslemiate cio serene osteo cie taaciohsters ererenterets 
Three views of aright valve of this small species. Trenton shales, Fountain, 
Minnesota. 
PP RUMCELAY MEN CED ISS LMA 0) VSD aparetetote bstorer eye ve oles lpia at eistetalel tele = ust= eters iateye ea teiater ie stegetstcietets 
A left valve. Trenton shales, Fountain, Minnesota. 
SCHMID TH EGA SIN GOMPETA, MLS I sistets or e1-t lr ioke hel stalciet ish cholsieisverelatere)s xis oe eretsinezeiatsiaielele siete 
(See also plate xLim, figs. 39—41.) 
Interior of a left valve. Trenton shales, Fountain, Minnesota. 
Side and anterior views of a right valve; from the same locality. 
SCHMID TELIA S BRE VISj PM sO Pero vrois ouste cicheterereiel cute: oicteintavbstarstone ein tetetoterere cee fale mote terete, stoners 
Side and anterior views of a left valve. Trenton shales, Fountain, Minnesota. 
SCHMID DET TAU MEO NIAIAS ASD sires eratets Vote opel elstctajersjatniel as tite eteiaret teeters oloiokatelaeaPe teats Ietel 
Anterior and side views of a left valve (opposite alge restored). Upper third of 
Trenton shales, St. Paul. Minnesota. 
View of the interior of a right valve, from the same locality. 
SCHMID TELA. SUBRODUND As MHS Peis ost erereiole e'ereietelare siete erate rei tetersterc faye otete tel ete ralet d etetataife eat 
Side and end views of a right and left valve. In both cases the opposite valve 
has been restored. Lower third of the Trenton shales, Minneapolis, Minn. 
663 
663 
645 
637 
645 
639 
644 
638 
649 
651 
642 
642 
641 
643 
