Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Fig. 
Figs. 30 and 31. 
Figs. 32 and 33. 
Fig. 
1 and 2. 
3 and 4. 
5 and 6. 
12 to 
15 and 
17 to 
20 to 
20 to 
25 to 
14. 
16. 
19. 
34. 
PLATE XXXVII. 
ENDODESMA ORTHONOTUM Meek and Worthen, Sp.......-:..ceeceeeet cone ceeeeees 
Lateral and dorsal views of the original type of this species. The Baeenmien isa 
good cast of the interior, in solid limestone, of a left valve. All of it is now 
exposed, the tough matrix, which covered a considerable portion of the ventral 
margin when it was used by Meek and Worthen, having been removed before 
it was redrawn for the present work. Lower Trenton limestone, Dunleith, 
Hlinois. 
HINDODESMAsGESNIERT VUNG Sy S Piayretets ctete ls cteteletela\stek tos leletelenatatersierniaYetnlclenatelajeisietaeierieiainie 
Lateral and dorsal views of a good cast of the interior of a right valve. Trenton 
limestone, Ottawa, Canada. Introduced for comparison with the other species 
of this proposed genus. 
EX NDODESMAGPOSTIZA TUM, c1e8 Diese cisiclehs's wi ctavotels ese ail cfs ors nrsirete exeinle ereiersteners)otelolemtaseieter= 
Lateral and dorsal views of an internal cast. Upper Galena, Dubuque, Iowa. 
Geol. Survey Museum Reg. No. 8345, 
ORTHODESMA CANALICULATUM, “1. SP. coe scicie ceieenis «te ts sine seein es 04 Siaiemiveisie «/eirlm els 
The right side and a dorsal view of a nearly entire cast. Waynesville, Ohio. 
Well preserved but incomplete cast, showing the anterior end and obscure rays 
across the central half. Upper beds of the Cincinnati group, Waynesville, Ohio. 
Posterior two-thirds of a cast from the Hudson River group near Spring Valley, 
Minnesota. The length of this specimen was reduced by pressure, and to this 
cause we must ascribe the more crowded arrangement of the radiating lines. 
View of the broken end of same, showing the natural convexity of the valves 
and the cardinal depression. 
ORTHODESMA MINNESOTENSE Ulrich 
The left side of the type specimen. 
Dorsal view of same. 
Anterior part of a dorsal view, x 4. Middle third of the Trenton shales, Minne- 
apolis, Minnesota. 
MODIOLOPSIS CONCENTRICA Hall and Whitfield. ...................0 cece e eens 
Eero of the shell as obtained from a gutta-percha impression of a natural 
mold. 
Finely preserved cast of the interior. In offering these figures I wish it to be 
understood that the specimens selected are strictly normal for the species as 
it occurs in Ohio. Further, that the species is very constant, and that all 
marked deviations in contour which may be observed in a series of Specimens 
are the result of distortion through pressure. 
{VEAN UX MIAT SA RTD ESO NUL Mtl Chas rcye eye. avaratascnese, sinalets ayer etctastrsunteyacatovere’s tre ilonn oier etch ag tare Tere 
(See also plate xxXviil, fig. 45.) 
Lateral, anterior and cardinal views of the pest cast seen. Trenton limestone, 
Minneapolis, Minnesota. 
MODIOLODON SEA U US 1s) SP) se: aera ele ose nit nlay ape eteretekaiayey ove iarefaratete isrcleyaiattiet=ttereVeterslete eiereteneTs 
The left side and anterior and dorsal views of a cast. Lower or middle Galena, 
Decorah, Iowa. Geol. Sur. Mus. Reg. No. 8363. 
The left side of a cast of the interior from the Trenton at Danville, Kentucky. 
A small specimen from the middle Galena of Goodhue county, Minnesota. 
CrENODONTA-PLANODORSATA, (WITCH Yet semi wie seit cateerniels »<\aie oelelsie aetle siamiterenieies 
(See also plate xu, figs. 38 to 40.) 
Posterior view of the original type. 
Right valve of same, with a small part of the surface magnified. 
Profile in a postero-basal view 
Cardinal view of same. Upper part of middle third of Trenton shales, Goodhue 
county, Minnesota. 
CTENODONTANCOMPRESS A SU Clie, 5 sepcrers res oie oi ets wicle/ote i oielaaveleneis aiotevalene ie evoke slereln ieee terse 
(See also plate xxit, figs. 88 to 90.) 
The original type of the species, x 1.3. Upper part of the middle third of the 
Trenton shales, Goodhue county, Minnesota. 
GCrENODONTA: TONGA. UIDICH oxides ccys ee ees wake SR aaa eis ote ce ee tate nsbonste eteraiielosie 
Interior of the right valve upon which this species was founded, magnified twice 
and of the natural size. Middle third of the Trenton shales, Goodhue county, 
Minnesota. 
CLIDOPHORUS 2 CONSUETUS WIT Chitin iain cictecitl-isieietetelel-1o'-spsiclecie ei ieciae ieraeheeaiae lotsa 
The type specimen of the natural size and magnified twice. Middle Galena near 
Wykoff, Minnesota. 
TECHNOPHORUS, EX THNUATUS) (Wiliriehicyts erates specail ctevercisinietare c)eteleletetelelelere cters/oniieeteeters 
View of the left side of the cast of the interior upon which the species was 
founded. Middle third of the Trenton shales, Minneapolis, Minnesota. 
