Wigan, 69 and 60, 
Oo. 
00, 
Wigs, 61 to i, 
OL, 
02. 
68 and 64, 
Wigs. 65 and 06, 
Piga. 07 to 7, 
67 and U4, 
60, 
10 to 72. 
vin 
Wiga, 74 and 7, 
UA, 
75, 
Wigs, 76 to 82, 
7 to 78, 
vin 
80, 
Al and 82, 
Wigs. 88 to AY, 
83 and 4, 
86 to 87, 
Wiga, 88 to 90, 
BA and HO, 
0, 
Figa 01 and 02, 
Wigs, 08 and 04, 
Wiga, 06 to 07, 
5 and 06, 
07, 
Figa, O08 to 101, 
08 to 100, 
101, 
Higa. 102 to 106. 
102, 
108, 
104 to 106, 
OTMBNODONTA BOOCLIALIS, H. Ap,. vere een 
PLATE XLIL.— Continued. 
Paan, 
PTET Teeter spe dy apne eds ade Cr daycates ecabacaea® sevccee) O06 
Outline views of three spec mene of ‘Aiiferent slvos and showing slight varlations In form, 
Hinge of two right valves, * 4, showing slight differences In the wnterlor parts, 
OTENODONTA CALVINI, 1. AD... 506 
An excellent cast of the totertor of a left valve, showlng muscular sears and rays more plainly than 
usual, In this specimen the length aiso ta a little greater than in the others, 
Another cast of a loft valve, Minn, Geol, Sur, Mus, Reg, No, 8628, 
Lateral and cardinal views of a cast of a right valve, representing the usual characters of the species, 
OPTMNODONTA MADISONDNAIB, D. AD. ce. ee PPrev ery tery vine idhgias Paseinehd.a shes kedl's tekied pond date vaadset. .00e 
The loft alde and an antertor view of a toat iferous oxample of this spectes, 
OCTEMODONTA FEOUNDA TOL) veccccussvvissebovencatsucvvvesubenev ev havut sey teas thy bareee qeeecscepesduacsscsivoges (OOD 
The right alde and an anterior view of & cast of the Interfor, Tn many specimens the ‘postertor 
margin Is more rounded 
A small part of the external surface magnified to show the fine concentric und radiating lines, 
Cardinal and anterior views and the right side of # apecimen preserving the shell, 
The wavy hinge line as shown on & oust of the Interlor, ¥ 6, 
OPBHNODONTA BIMULATIIX, Te AP ..cce ceee ashe ba viet bate rstimuversvabpase %OUU! 
A cast of the lnterior of a right valve, showing the muscular sears and retaining a Hittle of the shell 
about the beak, 
As much of the hinge as ean be made ou t from the preceding specimen, 
OPMNODONTA ALMMONTINA, 1. APs... Cevesese Cvvveeveee vovereence Ceeeeeeee sae eeerenueereecees vésncceessigteSeecdepe ODO 
Throe views of w large specimen having the posterior ond a little narrower than usual, 
A sronllor spoctmon of the usual form, 
Hinge of # large and smaller right valve, showlng the subrostral pit and the geniculated teeth, 
Oardinal and lateral views of a cast of the Interlor which retains a part of the hinge, 
OPBNODONTA ODLIQUA Tall. ....6 cece cece ee dy ivgheah uemiselnihs Vsisen tow a ieaWaraniste eines koe ay . O04 
Literal and cardinal views of 2 small specimen of ‘the large northwestern varloty of this species, X 5. 
As usual, the specimen is a cast of the Interior and shows the muscular sears and impressions of the 
hinge donticlos very cloarly, 
Three Internal casts of u smull form of the species from the Olnetnnat! group of Ohio, x 6. 
OTHNODONTA COMPRMBBA ULPION ccc ccccce cert eeee ee reece i sedeeetacceve covepecs’ sececevesiioveenscccsussenveeece 600 
(Soe also plate XXXVUT, fly, 20.) 
Posterior and lateral views of a left valve, 
The greater part of the hinge of another left valve, ¥ 6, showing the various parts In a beautiful 
state of preservation, 
OPMNODONTA HAMBURGENSIS WalCOtt coccceccccce cee vvenevesepede sve eecorreaceccres fecphsenocsacsecccensvesecens OOD 
A right(?) valve of the natural size and x 6, 
OPHNODONTA ALTA ILall, vedeneesens wa dacy spesavedvcseess patocvereTabsseertercesss Suyet bas, C0Um 
Lateral and postortor views of a cast of the: ‘nterior, 
OTMNODONTA INTHRMEDIA UIPlOh oc. ee cee Geceesecedves tases s -sevensioe oaanecn, @. poecled Uevsresovecisancsenvsset | COL 
Lateral and posterior views of a right valve preserving much of the shell, The opposite valve is 
rostored in the profile view. 
A sharply marked cast of the Interlor of a left valve. In this specimen the posterlor extremity is 
unusually produced, 
OTHNODONTA RHOURVA UITICH, 66. cece ce eeeee veel savevewews ndghedecndipey ctdtdveavs vias sughjs CUD 
Postoerlor, lateral and cardinal views of a perfect apuclmon of this species, showing the usual form, 
the antortor sulcus and the sharply defined anterior and posterior lunettes, 
The greater part of a hinge of a left valve, * 2, showing the arrangement of the denticlos, the 
sharply elovated outer margin and the ligamental area on the right side of the beak, 
OPTHNODONTA AIMILIS Ulrich,.... veseeevesaees se segpeosrenes J Ee vores nae visa neds bar ceneeeeesneeee de ceens avcovses:! O06 
Hinge of u loft valve of this apocios, & 2, showlog the principal features upon which this species is 
separated from O, recurva, (See fig, 101) 
The left side of a specimen, showlng the usual form of the species, 
No, 8868, 
Lateral, cardinal and posterior views of a specimen having an outline very similar to that of 
O. recurva, But the absence of the anterior suleus, the greater convexity of lis valves and the 
los# sharply defined lunettes are all charactoristic of O, similis and prove its distinctness from 
O, recurva, 
Minn, Geol, Sur, Mus, Reg, 
