Figs. 
Figs. 
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Fig. 
PLATE XXXIX. 
PaGe. 
1=to- (5; SVANUXEMEAY DEGLELENS,: 1s SPs.4 cers) aminetemtlin one = sarelloiatel stern ale serererateiett ae nie is estetersiese 562 
yi) 5 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. 
6 and 7. VANUXEMIA WORTHENT (UW 1TiChy.(.6 oc ciicre wistaiel leveyotoes crstensilats er elale  ofelistelatatatetels ieletel=t=intae 561 
The left side and an anterior view of a nearly perfect cast of the interior. Upper 
Galena, Jo Daviess county, Illinois. 
8) to-12., CYRTODONTA: OBESA, sTla SP iiorecr euler telereielerataveteretevetate ete relate tatetetetetey afer ete ovale = (el-TatsTolc\alsyelate Vel ieis 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 to 15. CTENODONTA GIBBERA, TD. SP. o ici ccinecsceceinesiseeeess >= ™eigsies scien: boushiecdaue 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. 
16: to) 19 ‘CYRTODONTA! RO TUT AWA MINS Spero cteteraicveielal clears tote mastste dete eeterete ts iokel siete ete) ti\-fatelateiateleds lots = 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)-t0- 23) ‘CYRTODON DTA AREENTS Hens Drsetccisunraisisic (fee clare ein cielo ct atensiasiet cfareteyoyofalete(=feteistereiefeiiats iefeleyeiat= 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. 
A-and/25: -CYRTODONTA PAR VA, TSP iaajaleecorcicicr ete -teielolsfele sfetayeielernie oisis iors eke Oielstnlatefatarastein\sielstala’>l=(elciarst= 541 
The left side of an entire cast of the interior of the natural size and x 2.3. 
Middle Galena near Fountain, Minnesota. 
26 and 27. CYRTODONTA JANESVILLENSIS, 0. Sp.....--- RAS Foie Want SATS Gone SEAS aca 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. 
28 to 33. and ?45. CYRTODONTA SUBOVATA, D. SP...cc csc ceccsccececccr seen saeecsrnsrseswsccoss 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. 
4 CXR TODON TA CAMPIGAG OIluS Diesels iiersiste/aieicisisie eieteleletaterelniat ey eimiou locates alee) slot cJuuevaraysielsyalofetare aie 538 
An imperfect cast of the interior of a large left valve. Trenton limestone, 
Cannon Falls, Minnesota. 
85 and 36. CYRTODONTA OBLIQUA Meek and Worthen...:... .....2.0c0ccccencencovenens vers 540 
The left side and a front view of the original type of this species. Illinois State 
Museum. Galena limestone, Scales Mound, Illinois. 
37, to) 40h ‘CY RTODONTA, 'GUABET TW AMUUET CI rere 0 cislste «icte!e) aie eal snrereiers ofeletaieeveital talo\eyole)aete siateteta lease i= 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, 
41 to 44. CYRTODONTA PERSIMILIS, TM. SP.c... 0... ccc cee cee secs cet weet ese sseructscsaencs 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: CYRTODONTA OVIFORMIS WTICD ence fe os cess puece «in » sibeialele}sisinleceiele)=ielalsiniele\eisieleleleis/e\s/s/= 544 
(See also plate xu, fig. 1.) 
Mold of the interior of a left valve, with a portion of the shell remaining. 
“Lower Blue” beds of the Trenton formation, Janesville, Wisconsin. 
