NO. 3 BURGESS SHALE FOSSILS — WALCOTT 7 



finer and extend farther back on the anterior end. The annular Hnes 

 and interspaces are also finer and more irregular." 



Several specimens, among the many found subsequent to 191 1, preserve some 

 of the structure features very well, and illustrations were prepared by Doctor 

 Walcott to show them. However, it is very doubtful whether tlie forms shown 

 on plate 9, figures 2 and 4, belong to this species. 



Plesiotypes. — U. S. N. M., Nos 83939a-g. 



PIKAIA Walcott 191 1 



PIKAIA GRACILENS Walcott 



Plate 8, f^gs. 4-5 



Pika'ia gracUcnx Walcott, 1911, Smithsonian Misc. Coll., vol. 57, p. 132, pi. 20, 

 figs. 1-2. 



Original description. — " Body elongate, slender, and tapering at 

 each end. It is formed of many segments that are defined by strong 

 annular shiny lines. Head small with two large eyes and two tentacles 

 as shown by figure i. Back of the head the first five segments carry 

 short parapodia that appear to be divided into two parts. 



" The enteric canal extends from end to end without change in 

 character. It is relatively large along the central portions and tapering 

 toward the ends. Judging from such specimens as the one illustrated 

 by figure 2, its annulations correspond in size with those of the body. 



" Surface apparently smooth. Two entire adult specimens and 

 several fragments of others indicate a length of about 5 cm." 



Two additional figures are presented at this time. 



Plesiotypes.— IJ. S. N. M., Nos. 83940a-b. 



SELKIRKIA Walcott 191 1 



SELiaRKIA MAJOR (Walcott) 



Plate 10 



Ortliotlieca major Walcott, 1908, Canadian Alpine Journ., vol. i, p. 24ri, pi. i, 



fig. II. 

 Sclkirkia major Walcott, 191 1, Smithsonian Misc. Coll., vol. 57, p. T20, pi. 19, 



fig. 6. 



This species was first described from the Stephen formation on Mount Stephen. 

 Later Doctor Walcott found apparently the same shell at the Burgess Pass 

 quarry, but in this instance the soft body of the animal was preserved and there- 

 fore, in the 1911 discussion, he removed it from the Hyolithidae to the poly- 

 chaetous annelids. 



Photographs of two exceedingly well preserved individuals with the body 

 extending beyond the shell are printed here for the first time. 



Flt'siotypi\<;.—\J. S. N. M., No. 8394 la-b. 



