296 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



DESCRIPTION OF PLATE 45 



PAGE 



Neolcnus serratus (Rominger) 277 



Fig. I. (Natural size.) A specimen showing on the left side 12 thoracic 

 abdominal legs and portions of three imperfect cephalic legs, 

 also antennae and one of the caudal furca. U. S. National 

 Museum, Catalogue No. 58588. 



2. (Natural size.) A specimen showing thoracic-abdominal legs 



and how they vary in length beneath the pygidium. This 

 variation would necessarily make the imprints of the ter- 

 minal joint occur at varying distances from the median 

 line as represented by the base of the caudal furca. The 

 posterior legs on the left side have three short spines 

 attached to the distal end of the terminal joint. U. S. 

 National Museum, Catalogue No. 58589. 



3. (X2.) Cephalic legs projecting forward. U. S. National 



Museum, Catalogue No. 58590. 



4. (X2.) Legs showing terminal joint with trifid termination. 



Such legs would make an imprint similar to the trifid tracks 



on plates 48 and 49. L^. S. National Museum, Catalogue 



No. 58591. 



The specimens represented by figs. 1-4 are from locality (35k), 



Middle Cambrian, Burgess shale member of the Stephen formation, 



on the west slope of the ridge between Mount Field and Wapta Peak, 



one mile (1.6 km.) northeast of Burgess Pass, above Field, British 



Columbia. 



