214 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



DESCRIPTION OF PLATE 27 



PAGE 



Burgessia bella Walcott ( see pi. 30) 177 



Fig. I. (X3-) Dorsal view of a specimen showing the internal struc- 

 ture through the thin carapace, st = stomach, i = intestinal 

 canal, kd = hepatic caeca, cl = connection between hepatic 

 caeca and alimentary canal, thl^ thoracic legs, ab = al)dominal 

 region, but the segmentation is not preserved in this speci- 

 men. U. S. National Museum, Catalogue No. 57676. 

 2. (X3-) Ventral view of the region beneath the carapace. Letter- 

 ing the same as for figure i with the addition of a' = antennae, 

 lb = labrum. U. S. National Museum, Catalogue No. 57677. 

 3- (X3-) Dorsal view of area within the cephalic shield, showing 

 interior and appendages of the head. e = eye, a" = antennae, 

 3, 4, 51= cephalic appendages, th = base of thoracic append- 

 age. Other lettering as in figures i and 2. U. S. National 

 Museum, Catalogue No. 57678. 



Waptia Heldensis Walcott 181 



Fig. 4. (Xi.5-) Dorsal view of a specimen flattened on the shale, 

 c = carapace, e = eye, a' =^ antennas, thl = thoracic legs, cr 

 = caudal rami. U. S. National Museum, Catalogue No. 

 57681. 

 5. (X2.) Side view with carapace (c) pushed over forward so 

 as nearly to reverse the position of the dorsal line, th = 

 thoracic segments, thl = thoracic legs, ab = abdominal seg- 

 ments, cr = caudal rami, m = mandible, m' = maxillula, m" = 

 maxilla, br = gill lobe. U. S. National Museum, Catalogue 

 No. 57682. 



Opabinia regalis Walcott (see pi. 28, fig. i ) 167 



Fig. 6. (X2.) Lateral view of the type specimen of the male of the 

 species. The eyes (e) are crushed one beside the other, fp 

 = frontal appendage, ths = trunk somites, br = gills. f = 

 terminal lobe-like joints of thoracic legs, t = telson or ter- 

 minal somite. U. S. National Museum, Catalogue No. 57683. 



All of the specimens illustrated on Plate 27 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. 



