SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



PAGE 



Tontoia kzvagnntensis, new species 199, pi. 24, fig. 4 



transitans, see Nathorstva. 



Trenton limestone 190 



triangulata, see Hurdia. 



Triarthrus becki, mentioned 190-191, 192 



Trilobita, subclass, discussion of Neolenus and Ptychoparia 190 



beginning with Nevadia 157 



classification of 154 



descent of 160-161 



different line of descent 164 



possible form between Branchiopoda and Aglaspidse 163 



relations of, to Branchiopoda, Leptostaca, Malacostraca, and Meros- 



tomata , 163 



segmentation, table of 158 



Sidneyia, relation to 206 



mentioned 148, 153, 155 



Trinucleus concentricus, mentioned 190 



Tuzo, mountain in Alberta, Canada 187 



Tiizoia, new genus, discussed 187 



bivalve carapace of 157, 158 



classification of 154 



compared with Nebaliopsis typica Sars 165 



(footnote) 154 



Tiizoia retifera, new species 187, pi. t,^, fig. 2 



compared with Nebaliopsis typica Sars 187 



stratigraphic position and association 153 



Upper Cambrian, representatives of Merostomata in ISS 



Utica shale 190 



varians, see Scenella^ 

 vcnnicatida, see Hymenocaris. 

 venosa, see Carnarvonia. 

 victoria^ see Hurdia. 



Waptia, new genus, discussed 181 



approach to Leptostraca 163 



classification of 154 



rami and segmentation 159 



shield of 157 



stratigraphic position and association 153 



Waptia Heldensis, new species 181, pi. 27, figs. 4 and 5 



appendages of 182 



compared with Bidentia difhcilis 174 



compared with Yohoia tenuis 173 



resemblance to Neolenus serratus 191 



stratigraphic position and association 152-153 



Waptidae, new family, described i8c 



classification of 154 



compared with Branchiopoda and Malacostraca 180 



