232 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53 



Description of genera and species 256 



Nevadia, new genus 256 



weeksi, new species 257 



Mcsonacis Walcott 261 



niickwitzi (Schmidt) 262 



torelli (Moberg) 264 



vermontana (Hall) 264 



Elliptocephala Emmons 267 



asaphoides Emmons 269 



Callavia Matthew 274 



bicensis, new species 2.TJ 



broggeri (Walcott) 279 



burri, new species 280 



callavei (Lapworth) 282 



cartlandi (Raw) (MSS.) 282 



crosbyi, new species 284 



? nevadensis, new species 285 



Holmia Matthew 286 



kjerulfi (Linnarsson) 288 



lundgreni ( Moberg) 290 



rowei, new species 292 



Wanneria, new genus 296 



? gracile, new species 298 



halli, new species 301 



walcottanus ( Wanner) 302 



Paedeumias, new genus 304 



transitans, new species 305 



Olenellus Hall 311 



argentus, new species 314 



canadensis, new species 316 



? claytoni, new species 319 



f rcmonti, new species 320 



gigas Peach 323 



gilberti Meek 324 



gilberti, variety undetermined 331 



lapworthi Peach 331 



logani, new species 333 



reticulatus Peach 335 



thompsoni (Hall) 336 



thompsoni crassimarginatus, new variety 340 



? walcotti (Shalcr and Foerstc) 341 



? sp. undt. Sweden 341 



? sp. undt. Scotland 342 



Peachella, new genus 342 



iddingsi (Walcott) 343 



Olenelloidcs Peach 345 



armatus Peach 347 



Alphabetic list (arranged by genera, subgenera, and species) of the 

 forms now placed in the Mesonacidae, as they occur 



in the literature, with the present reference of each.. 351 



Ribliography 372 



Description of plates 380 



I ndex A2X 



