112 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 57 



As in the case of the holothurians the annehds go to prove that the 

 Cambrian fauna was highly developed and differentiated in pre-Cam- 

 brian Lipalian time.^ 



ANNULATA 



Class CH^TOGNATHA 



AMISKWIDJE, new family 



Chgetognatha allied by external form to Sagitta. Body divided 

 into a head, trunk, and tail. One pair of lateral fins. An interior 

 septum occurs between the head and body, but none is shown be- 

 tween the body and tail. 



One genus, Amiskwia. 



AMISKWIA, new genus 



As there is but one species the generic and specific descriptions 

 will be combined under the species. 



Genotype. — Amisktina sagittiformis, new species. 



Stratigraphic range. — The stratigraphic range is limited to a band 

 of dark siliceous shale about 4 feet in thickness forming a part of 

 the Burgess shale member of the Stephen formation. 



Geographic distribution. — On the slope of the ridge between 

 Wapta Peak and Mount Field, north of Burgess Pass, and about 

 3800 feet above Field on the line of the Canadian Pacific Railway, 

 British Columbia, Canada. 



Observations. — Amiskwia resembles Sagitta superficially, but 

 differs from the latter genus in the form of the head, the presence 

 of strong tentacles, the absence of a hood about the head, the strong 

 single pair of lateral fins, and the absence of a posterior septum. 



Generic name derived from Amiskwi, name of a river west of 

 Mount Burgess, British Columbia, Canada. 



AMISKWIA SAGITTIFORMIS, new species 

 Plate 22, figs. 3 and 4 



Body cylindrical and divided into a broadly elongate oval head, a 

 cylindrical body, and an expanded tail. The head, expanding from 

 the neck, contracts to a bluntly pointed anterior end, from the 

 rounded angles of which project a pair of strong tentacles. The 

 lateral fins of the body are a little more than one-third the length of 



^ Smithsonian Misc. Coll., Vol. 57, No. i, 1910, p. 14. 



