2 SMITHSONIAN MISCELLANEOUS COLLECTIONS \0L. 85 



INTRODUCTION 



It is obvious that one person cannot cover, even in a very cursory manner, 

 the entire field of Cambrian stratigraphy and paleontology, especially with such 

 rich faunas as the Burgess shale extant. Again, in the case of the Burgess 

 shale faunas, none but a trained student in biology can do more than merely 

 assign specific and generic names to the gross forms. Further, it is doubtful if 

 any biologist, however versatile, could by long years of study perceive every- 

 thing to be learned from these wonderful fossils. In view of these facts it has 

 seemed advisable to encourage specialists to study the various classes repre- 

 sented rather than attempt to monograph the subject as a whole. Accordingly, 

 such a study by Dr. G. E. Hutchinson has recently been printed * and one by 

 Dr. Rudolf Ruedemann has been submitted for publication.^ In this way we 

 may hope to carry on the work suspended by the passing of the discoverer of 

 these unique forms. 



The following descriptions either were prepared entirely by Doctor Walcott 

 or are based on notes and illustrations left by him. 



formation and locality. — For every species described in this paper, the for- 

 mation and locality are as follows: Middle Cambrian, Burgess shale: (Loc. 

 35k) on the west slope of the ridge between Mount Field and Wapta Peak, 

 I mile (1.6 km.) northeast of Burgess Pass, near Field, British Columbia. 



DESCRIPTION OF GENERA AND SPECIES 



MARGARETIA, new genus 



The characters of this strange organism are presented in the specific descrip- 

 tion or shown in the illustrations. 

 Genotype. — M. darns, new species. 



MARGARETIA DORUS, new species 



Plate I, figs. 1-6 



More than 70 specimens of this peculiar organism have been assembled froiu 

 the Burgess shale collections. In the following description comparisons are 

 made with algae. Other notes by Doctor Walcott, apparently his latest, together 

 with suggestions by Mr. A. H. Clark, and particularly the presence in the same 

 drawer of specimens of Titanideum suberosum, indicate that Doctor Walcott's 

 latest opinion was that M . doru.<! might really be an Alcyonarian. 



Description. — Mass forming a thin membranous perforated slieet, 

 narrow at the base and expanding to a width of 1.5 cm. in 2 cm. 

 distance; length of narrow base about 1.5 cm. and of wider portion 

 4 cm. ; the perforations are elongate oval and apparently arranged on 

 longitudinal and obliquely transverse lines ; tegument presumably 



' Restudy of Some Burgess Shale Fossils. Proc. U. S. Nat. Mus., vol. 78, 

 art. II, pp. 1-24, pi. I, year ? 



'Some New Middle Camb!-ian Fossils from British Columbia. To be printed 

 in the Proc. U. S. Nat. Mus. 



