436 



INDEX — GLOSSARY 



Odontoceti, 399. 



Odontophore, in gastropods, 236. 



(Esophagus, see esophagus. 



Oil-glands, 324. 



Old age characters in shells, 18. 



Oldhamia, 40. 



Olecranon process of ulna, in the cat, 



3^5- 

 Olfactory lobe of brain, of alligator, 372 ; 



of Ichthyornis, 373 ; of tern, 372. 

 Oligocene, 407. 

 Oligocene fossils figured, Q3, 3S8, 3QI, 



393, 394, 395- 

 Ommastrephes, 269-271, 273 ; 0. ille- 



cebrosa, 26Q ; distribution of-, 269 ; 



eyes of, 270; food of, 270; funnel of, 



26Q, 270, 271; hearing of, 271; ink 



sac of, 270 ; jaws of, 26Q ; locomotion 



of, 270; otocystsof, 271 ; sexes of, 271; 



skeleton of, 26Q, 270 ; suckers of arms, 



270; tentacles of, 26Q. 

 Ommatideum, of crayfish, 282 ; of 



crustaceans, 282. 

 Onoclea, 43, 46, 47, 48 ; O. inquirenda, 47 ; 



O. sensibilis, 47, 48. 

 Onondaga formation, fossils from, 263; 



geologic range of, 263. 

 Ontogeny, the life history of an 



individual organism from the egg to 



adulthood. 

 Onychophora, 275, 308; fossil, 308; 



geologic range of, 409. 

 Oolites, 2,3, 34- 



Ooze, diatomaceous, 34 ; foraminiferal, 

 • 89 ; globigerina, 89, 90 ; radiolarian, 



94. 

 Operculum, of fishes, 344, 346; of gas- 

 tropods, 235, 239, 244. 

 Ophioglossales, 46. 

 Ophiopholis aculeata, 165. 

 Ophiuroidea, 165; geologic range of , 165, 



409. 

 Opisthobranchia, 243, 244, 248. 

 Opossums, 378. 

 Optic lobe of brain, of the alligator, 273; 



of Ichthyornis, 372 ; of the tern, 372. 

 Orang-utan, 400. 

 Orbit of eye, of birds, 372 ; of cat, 325, 



335; of mammals, 325, 335, 385; 



of ostracoderms, 338 ; of reptiles, 360, 



367- 

 Orbitoides, 88, 92, 93. 



Ordovician, 407. 



Ordovician fossils figured, 36, 37, 114, 

 118, 119, 120, 133, 156, 178, 196, 197, 

 200, 201, 244, 262, 286, 296, 297. 



Oreodon, 397. 



Oreodonts, 397. 



Oreomunnea mississipiensis, 81. 



Oreopithecus, 400. 



Organic matter, growth of, 2 ; vs. in- 

 organic matter, i. 



Organisms, naming of, 24. 



Organ-pipe coral, 128, 135. 



Ornithopoda, 363-364. 



Ornithorhynchus, 3 78; hatching of eggs 



of, 377- 



Orohippus, 393, 394. 



Orthis lenticularis, 200. 



Orthoceras, 262 ; O. sociale, 262. 



Orthoptera, 318. 



Osculum, of sponges, 96, 99, 104, 106. 



Osmosis, the tendency of liquids or gases 

 of differing densities to mix through a 

 porous structure. 



Osmunda, 46. 



Osmundaceae, 46. 



Osmundites, 46. 



Osphradium (plu. osphradia), of cepha- 

 lopods, 255, 258; of gastropods, 238; 

 of pelecypods, 213, 221. 



Os pubis, see pubis. 



Ostracoda, 303-304, 306; see also 

 ostracods. 



Ostracodermi, 337-338; geologic range 

 of, 338, 409; habits of, 338; place in 

 classification, 337. 



Ostracods, 303-304, 306; compared to 

 young barnacles, 305 ; eyes of, 303, 

 304 ; fossil, 304 ; geologic range of, 

 303 ; habitat of, 303 ; shell of, dis- 

 tinguished from pelecypod shell, 303 ; 

 skeleton of, 303, 304. 



Ostrea, 225-226; O. virginica, 223; 

 attachment of shell, 226; blood of, 221 ; 

 bored by Cliona, 226; composition of 

 shell, 25 ; effect of loss of one muscle 

 upon shell, 222; fossils of, 226; 

 resilium (internal ligament) in, 221 ; 

 sex in, 221. 



Otocyst, method of functioning, 283 ; 

 molting of, 283; of cephalopods, 258; 

 of crustaceans, 283 ; of crustaceans 

 compared to the semicircular canals of 



