192" SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



Ptychoparia cordillercB (Rominger). — A small specimen, with the 

 dorsal shield exfoliated (pi. 24, fig. 2), shows an antenna and a 

 long series of the setiferous or filamentous exopodites. A specimen 

 recently worked out shows narrow, elongate, fringe-like appendages 

 attached to the setiferous branchial appendages that are similar in 

 appearance to the abdominal branchial appendages of Sidneyia.^ 



In the near future I wish to review the conclusions published in 

 my paper of 1881/ and those that have been entertained regarding 

 Triarthrus hecki and the new material from the Burgess shale. 



DESCRIPTIONS OF NEW GENERA AND SPECIES 



Order (undetermined) 



MARRELLID.ffi, new family 



Carapace strong, small, subquadrangular and with two postero- 

 lateral spines comparable with the lateral lobes of the carapace of 

 Apodidse. Eyes sessile. Head with five pairs of appendages. 

 Thorax with 24 pairs of appendages. Abdomen a single plate-like 

 telson. Thoracic leg with jointed leg-like endopodite, a jointed 

 setiferous exopodite, and expanded gill-like epipodite. 



One genus, Marrella. 



Observations. — This family is instituted to include Marrella splen- 

 dens, a species that, despite its remarkable carapace and cephalic 

 appendages, recalls Apus and Lcpidurus. It differs from the two 

 latter so markedly in its carapace and abdomen that it becomes the 

 type of a family that is less primitive than the Apodidae and may be 

 considered as near the Trilobita (p. 162). 



MARRELLA, new genus 



The generic description is included with that of the species. 



Genotype. — Marrella splendens, 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 betw^een 

 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. 



The generic name is given in recognition of the geologic and 

 paleontologic work of my friend. Dr. John E. Marr, Johns College, 

 Cambridge, England. 



^ Smithsonian Misc. Coll., Vol. 57, No. 2, 191 1, pi. 2, fig. i ; pi. 6, fig. 3 ; pi. 17, 

 fig. I. 



"The Trilobite, New and Old Evidence relating to its Organization. Bull. 

 Mus. Comp. Z06I., Vol. 8, 1881, pp. 208-211. 



