Figs 
Figs. 
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Figs. 
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Figs. 
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Fig. 
PLATE XXXIX. 
PaaE 
Ust0t og SVAN UXE MLAS (DE OLPIENS, | TSP ioe sect acces aerate norris Sao eee teu ae siete 562 
leetOntes: Lateral, dorsal and anterior views of the largest cast of the interior seen. 
4 and ‘5. Side and dorsal views of a smaller cast of a right valve. Geol. Sur. Mus., Reg. 
No. 8626. 
Grand ei. DVANU XEMPAY WORDEN | WilTiChsae coe. cec ee eegecctete ices ok tie ce eee SornONe 561 
The left side and an anterior view of a nearly perfect cast of the interior. Upper 
Galena, Jo Daviess county, Illinois. 
Sito 2s; CY RTODONTATOBESIA: GN nSDyeces as sees De fosetocstaue Oe PR iatmaioreic te Cela Plas ite Ina SPR Se 542 
8 to 10, Three views of a typical shell of this species. Black River limestone, Mercer 
county, Kentucky. 
11 and 12. — A small specimen of the natural size and x 2, referred to this species with some 
doubt. Middle third of the Trenton shales, St. Paul, Minnesota. 
13) FOp 524 CTENODONTASGIBBERA SUS )\-.e.. -nefctynccin none = aieteistaceiah reclame Sere ena hiatus ee 542 
Three views of the specimen described. It is a cast of the interior. Base of the 
middle Galena, Goodhue county, Minnesota. Mus. Geol. Sur. Reg. No. 8366. 
N6eto= 19 CVRTODONTAGRO TU ATA om, SPs. see Re eee cieiclomecinnciers sere een ome ere 541 
16 and 17. Side and profile views of a large internal cast, from the middle third of the 
Trenton shales near Fountain, Minnesota. Geol. Sur. Mus. Reg. No. 8336. 
18 and 19. Two views of the testiferous type of the species. Black River limestone, Mercer 
county, Kentucky. 
20> tO=23.. _CYRTODONTA ABMINIS, Di sSD\ sacs: cee sees eee sve vs) State hurePeersiglay aves eeiate eeuatenttat ENT arches, aia - 540 
20 to 22. Side and dorsal views, and the hinge of a right valve. Middle third of the 
Trenton shales, Goodhue county, Minnesota. 
23. A cast of the interior of the var. flllmorensis. Middle Galena, Fillmore county, 
Minnesota. 
2AtANGU29,. 1 CXR TOD ON TAS PIAR VA lon TSP iajeiaisiceicls intarsiaile aiated daevetele «i oarele or evsiatoie aa ets are een eee 541 
The left side of an entire cast of the interior of the natural size and x 2.3. 
Middle Galena near Fountain, Minnesota. 
26faNde2ies CXYRTODONTA JANES VIL LENSIS, MSPs acinericisic elaieaisiesove cistern heer ante sioner erate aioe 537 
Casts of a small right and a larger left valve. The central part of the surface in 
the latter is broken in the specimen, but has been restored in the drawing. 
“Lower Blue” beds of the Trenton, Janesville, Wisconsin. Geol. Sur. Mus. 
Reg. No. 8323. 
20) 00 dsandez4o, mi CYR TODONDA SUBOWAAN MSP /eiascacieaicie site ve sike cee oe eee eee noes 536 
28, 31 and 32. Three views of an entire and well preserved shell. Birdseye limestone. 
High Bridge, Kentucky. 
29. An old left valve from the Black River limestone, or the base of the 
Trenton of Mercer county, Kentucky. 
30. Right side of a cast of the interior from the middle third of the Trenton 
shales, St. Paul, Minnesota. ; 
33. The hinge of a right valve from High Bridge, Kentucky. 
45. A cast of the interior of a right valve which is doubtfully referred to this 
species. The hight of the specimen has evidently been reduced by 
pressure. Trenton limestone, Cannon Falls, Minnesota. 
34) CYRTODON DAs AMPTPAR OM SSD tin are ence ak Sete clcine oa c A aes we eae ees S538 
An imperfect cast of the interior of a large left valve. Trenton limestone, 
Cannon Falls, Minnesota. 
sorand 36.. CyYRTODONTA OBLIQUA Meek and Worthen... 2. 650.005. ose. cecceccicisaceeeeacice cle se 540 
The left side and a front view of the original type of this species. Illinois State 
Museum. Galena limestone, Scales Mound, Illinois. 
37) Co) 405," | CYRLODONTACGLABHLE AN UIT Cla: « seyvereIeere ataciosleneioteesi on aetna are aire oe eters 543 
37 and 38. Two views of the original type of the species. Middle third of the Trenton 
shales, Minneapolis, Minnesota. 
39 and 40. Two sharply defined internal casts of opposite valves, showing slight variations 
in the outline. Trenton limestone, Beloit, Wisconsin. 
Ale tO} 44 oe CYR TODON LAUPER SEMEL IS Mens Pinon clerk wis oles is0inve a ota folote tualo ane te eiare Persiataietann atente ee reetetere 544 
41 to 43. Three views of an excellent cast of the interior. ‘‘Lower Blue” beds of the 
Trenton formation, Beloit, Wisconsin. 
44. A small right valve from the limestone at Minneapolis, Minnesota. 
46> {CY RLODONTAOVIF ORMIS SUMED nus nic-tigts sees eels meietelan oiste 1e ohio me eateries 544 
Mold of the interior of a left valve, with a portion of the shell remaining. 
“Lower Blue” beds of the Trenton formation, Janesville, Wisconsin. 
