2l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



DESCRIPTION OF PLATE 28 



PAGE 



Opabinia regalis Walcott (see pi. 2y, fig. 6) 167 



Fig. I. (X2.) Dorsal view of a male specimen, flattened in the shale, 

 showing fp = frontal appendage, e =; eye, ths = thoracic 

 somites, i = intestine, ab = abdominal segment. U. S. 

 National Museum, Catalogue No. 57684. 



Nathorstia transitans Walcott 194 



Fig. 2. (X2.) Dorsal view of the type specimen of the species. It is 

 flattened and slightly distorted with the left side more or 

 less crushed in towards the center, a' = antenna, e = eye, 

 gs = genal spine, pi = pleura of thoracic segments, m = 4 

 joints of leg (mandible?), ta =: central or thoracic axis, i 

 = intestine, thl = thoracic legs, cr =: caudal rami. U. S. 

 National Museum, Catalogue No. 57685. 



Naraoia compacta Walcott 175 



Fig. 3. (X2.) Side view of cephalo-thoracic carapace with traces of 

 appendages showing through it. U. S. National iMuseum, 

 Catalogue No. 57686. 

 4. (X2.) Dorsal view of specimen described. U. S. National 

 Museum, Catalogue No. 57687. 



All of the specimens illustrated on Plate 28 are from locality (35k) Middle 

 Cambrian : Burgess shale member of the Stephen formation, on the west slope 

 of the ridge betwen Mount Field and Wapta Peak, one mile (1.6 km.) north- 

 east of Burgess Pass, above Field, British Columbia. 



