INDEX 481 



PAGE 



Oryctocara, new genus, described and discussed 23 



compared with Bathyuriscus 23, 25 



Oleiius '. 23, 25 



Oryctoccphalus 23, 25 



Oryctocara geikiei, new species 23, pi. i, figs. 9-10 



associated fossils listed 25 



mentioned 30 



Oryctocephalus, compared with Burlingia 16 



compared with Oryctocara .23, 25 



reynoldsi, mentioned 17, 25, 30 



stratigraphic position and association 211 



walkeri, stratigraphic position and association 211 



sp. undt., stratigraphic position and association 199 



O tusia, classification of 142, 148 



evolution of pi. 11 (pp. 140-141) 



Outside and middle lateral (Protractor) muscles, defined 157 



Ovando quadrangle, Montana, fossils in 57 



Owen, D. D., bibliographic reference 114 



Oivenella typa, stratigraphic position and association 180 



Packard, A. S., bibliographic reference 376 



on the eyes- of Limulus and trilobites 239 



Pcedeumias, new genus 304 



anterior glabellar lobe in 243 



compared with Mesonacis 266, 304, 306 



Olenellus 304, 306, 307, 308 



delimitation of genus 248 



development of, shown in diagram 249 



eye lobes in 239 



genal and intergenal spines in 237 



history of founding of genus 266, 304 



median spine the telson of Olenellus 245 



mentioned 236, 247, 250, 269, 309, 2>^7 



new genus, species referred to the genus listed 232 



notes on proposal of genus 304 



segmentation of cephalon 238 



stage in development of Mcsonacidce discussed 308 



Olenellus mentioned 313 



stages passed through in development of 308 



state in development of thorax defined 245 



stratigraphic distribution tabulated 251 



Pcedeumias transitans, new species 305, pis. 24, 25, 32-34, and 44 



compared with Elliptocephala asaphoides 310 



Olenelloidcs armatus 346, 350 



Olenellus claytoni 320 



Olenellus gilberti 310, 329 



Olenellus lapzvorthi 331, 332 



Olenellus logani 334 



Olenellus thompsoni 306, 307, 308, 338, 339 



Mesonacis vermontana 306, 308, 338 



