Ixviil THE PALEONTOLOGY OF MINNESOTA. 
(Ehlertella, 364. 
Oligocene, flora, 4. 
Oolina salentina, 35. 
Oolyte, flora, 2. 
Operculina, 45, 28, 47. 
arabica, 46. 
complanata, 45, 46, 52. 
var. granulosa, 46, 52. 
granulata, £6. 
granulosa, 46, £7. 
hardiei, 46. 
irregularis, 46. 
marginata, 46. 
studeri, 46. 
Operculum, 98, 105. 
Operculum minimum, 45. 
Orbicula filosa, 370. 
lamellosa, 364, 
squamiformis 356, 
truncata, 364. 
Orbiculoidea, 363, 364, 365, 367. 
lamellosa, 364, 366. 
morrisi, 363. 
Orbitolites reticulata, 64. 
Orbulina, 43, 28. 
acerosa, 43. 
continens, 43. 
granulata, var. areolata, 43. 
var. atra, 45, 
punctata, 48. 
universa,’43, 52. 
Oreodaphne, 5. 
Orthid, 417, 
Orthis, 417, 335, 373, 377-378, 398, 409, 422, 423, 435, 
441, 449, 451, 454, 455. 
wquivalvis, 435. 
amcena, 453, 
basalis, 442. 
bellarugosa, 434. 
biforata, 455. 
var. crassa, 458. 
var. lyna, 455 457. 
forma daytonensis, £55. 
forma reversata, 455. 
bisulcata, 470, 469. 
borealis, 433*, 409, 467. 
callactus, 421, 435. 
calligramma, 418, 420, 435. 
var. davidsoni, 417, 418. 
centrosta, 458. 
charlotte, 424, 425. 
circularis, 452. 
conradi, 449, 448. 
costalis, 419. 
crassa, 458, 458. 
cyclus, 445, 444, 
davidsoni, 420. 
defiecta, 422, 333, 421-424, 
dentata, 458. 
dichotoma, 436. 
disparilis, 418, 420, 449, 
electra, 439, 449. 
elegantula, 442, 458. 
emacerata, 445, 442, 444. 
erratica, 469. 
flabellites, 432. 
flabellulum, 431. 
fissicosta, 436, 435. 
germana, 301,312. 
gibbosa, 451, 452. 
hamburgensis, 440, 441. 
huronensis, 405. 
incurvata, 385. 
insculpta, 435, 336*. 
insignis, 381. 
iphigenia, 431. 
jamesi, 435. 
Jugosa, 446, 444, 
kankakensis, 488, 436. 
kassubi, 450. 
lyna, 455, 454, 
macrior, 445. 
media, 450. 
meedsi, 427, 421, 422, 430. 
var. germana, 428, 334, 421, 471. 
meeki, 445, 439, 444, 
michelini, 418. 
minneapolis, £46, 448. 
minnesotensis, 427. 
multisecta, 444. 
occidentalis, 336*, 454. 
pectinella, 424, 420-425, 427, 428, 430, 431, 433, 
437, 438, 439. 
var. semiovalis, 424. 
var. sweeneyi, 426, 421, 427, 428, 430, 467. 
perveta, 450, 446, 448, 449, 452. 
petre, 431. 
plana, 405, 
platys, 424. 
plicatella, 436, 418, 419, 421. 
ponderosa, 407. 
porcata, 432. 
proavita, 431, 421, 480, 432. 
resupinata, 418. 
retrorsa, 432. 
rogata, 441, 
sinuata, 432, 433, 455. 
stonensis, 453. 
striatula, 441. 
subsequata, 446, 409, 418, 421, 448, 450-454, 461. 
var. circularis, 452, 448, 453. 
var. conradi, 449, 333, 448, 450. 
var. gibbosa, 451, 448, 450, 452. 
var. perveta, 450, 448. 
subquadrata, 428, 418, 421, 423, 430-482, 435, 
437. 
sweeneyi, 426, 425. 
testudinaria, 441, 416, #18, 439, 442, 444-446, 
451, 457. 
var. emacerata. 445. 
var. meeki, 445, 442. 
tricenaria, 418, 335*, 381, 417-420, 422, 441. 
triplicatella, 435, 436. 
whitefleldi, 437, 438. 
Orthisid, 377. 
Orthisina, 877, 
diversa, 378, 380. 
verneuili, 378, 380. 
Orthisine, 377. 
Orthoceras, 77, 113, 317, 319, 320, 321. 
