Fgs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
10. 
11. 
12, 
13. 
14, 
15, tosgl9: 
15 and 16. 
Nie 
18 and 19. 
20 and 21. 
22 to 24. 
25 to 27. 
28 to 30. 
28. 
29 and 30, 
31 and 32. 
31. 
32. 
33 and 34. 
35 and 36. 
37 and 38. 
PLATE XL. 
CYRTOD ONTA (OVARORMIS® Uli Chearschts eres wteteieretotars atetstejensioneyperoto tapers Inve (e alt tect ea reemere 
(See also plate xxx1x, fig. 46.) 
Anterior view of the type. 
GYRTODONTAY BILUTNGS) MsiS Picci «cists felete ie eiclels ole otebote tse etel oloterate lee ela ate yeeetaa eee 
Cast of a right valve from the lower Trenton limestone at Cannon Falls, 
Minnesota. 
Three views of the best specimen seen. Lower Trenton limestone, Dunleith, 
Tlinois. 
Another specimen from the preceding locality. 
CYRTODONTAMCINGULATA AU ILC Mit oe 7 ayeietele toe eis aioleeie eet cu ete a apres ates eam ot tee eet rere 
Anterior view and the right side of the original type. Middle third of the 
Trenton shales, Minneapolis, Minnesota. 
CYRTODONTA GRANDIS Ulrich, and varietieS.........-...-wecseee seuss  dnishiae aes 
(See also figure 48, a-k, p. 547.) 
Cast of a large right valve of the var. germana Ulrich. Galena shales, Goodhue 
county, Minnesota. 
Cast of a small specimen from the middle Galena at Lime City, Minnesota. 
This specimen agrees better with the var. germana than with the typical 
form of the species. Geol. Sur. Mus. Reg. No. 4102. 
A small specimen (cast of a right valve) of the typical form. Middle Galena 
Wykoff, Minnesota. 
Interior of the original type of Cypricardites germanus Ulrich. Upper Trenton 
near Danville, Kentucky. 
Part of the interior of the var. luculentus Sardeson, as shown in a gutta-percha 
impression from a cast of the interior belonging to the Survey collection. 
A good cast of another right valve of the same variety and from the same 
locality. Upper beds of the Hudson River group, Granger, Minnesota, Geol. 
Sur. Mus. Reg. No. 8332. 
(CIDP aOR DON HWS ao p ir byA ODN Al tinrinco ouad pane oooaw ou noadd Gabo ds Hodadades.ouevor 
Lateral and anterior views of a large right valve. 
Hinge of same. The cardinal teeth are obscure in the specimen and may not be 
exactly as drawn. 
Anterior and lateral views of another right valve, differing from the preceding 
in being more uniformly convex. Upper part of the middle third of the 
Trenton shales, Goodhue county, Minnesota. 
VANUXEMIA HAYNIANA Safford, SPe vores reer eee eee eee ee ee ee eens eee enee ceeeeees 
(See also plate XXxXVIII, fic. 32, and text p. 479, fig, 36—Iv. 
Imperfect interiors of two right valves, showing slight mitterences in ie cardinal 
teeth. Upper Trenton, near Danville, Kentucky. 
PLETHOCARDIA! UMBONATA! UGiehie circ re ceperetacre eoreiee sheet ciior ala eiteleietatatel rake eee nstetete 
Three views of the type specimen. Upper part of the middle third of the 
Trenton shales, Goodhue county, Minnesota. 
PLETHOCARDEASSUBEREC TA sUilEICIiyercmapecis cre tckeretettste otaralateratolttclel siete talevelensistntcetatiniele nic elere 
Three views of the typespecimen. Galena shales, Goodhue county, Minnesota. 
WHITELLA QUADRANGULAR!S Whitfield, sp ....--....+---.0 esses ee een eee e seen 
An imperfect specimen doubtfully referred to this species. Hudson River group, 
Spring Valley, Minnesota. 
Lateral and antero-cardinal views of a cast of the interior from Savannah, 
llinois. 
WHITEEGA (OBLIQ WAM AM WUTC yereretcteteterate sere ichelayStopate rate ale olelode le talelsteistetenejelotouslo lag) ste sine taa ie 
A cast of a left valve from the upper beds of the Cincinnati group, near Blan- 
chester, Ohio. 
The interior of a left valve, showing the hinge with its cardinal teeth, escutcheon 
and posterior internal ligament supports, and faint muscular impressions. 
The outline is imperfect posteriorly, causing the shell to appear less oblique 
than it should be. Hudson River group, Spring Valley, Minnesota. 
TECHNOPHORUS SUBACUTUS WITICh. 50.6.5... 6. ccc wcueninie ee ssele es mcitss = rinse 
Cast of the interior of the natural size and twice magnified. Trenton limestone, 
Minneapolis, Minnesota. Geol. Sur. Mus. Reg. No. 8338. 
TECHNOPHORUS FILISTRIATUS Ulrich <o.ck ve cc ccc sc were Pele nosis mepesiee eins c)eseivic esses 
Left valve of the natural size and a small portion of the surface enlarged to 
show the regular character of the fine concentric lines. Upper part of the 
middle third of the Trenton shales, Goodhue county, Minnesota. 
TTECHNOPHORUS DIVARICATUS UIrich .... 2.02.2... e ce cece wee e ees cee rene cetenees 
The type specimen, a perfect left valve, of the natural size and enlarged two and 
one-half times. Upper third of the Trenton shales, near Cannon Falls, Minnesota. 
545 
547 
546 
557 
576 
517 
566 
565 
614 
615 
616 
