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LOWER CAMBRIAN PTYCHOPARIID TRILO- 



BITES FROM THE CONGLOMERATES 



OF QUEBEC 



By franco RASETTI 



The Joints Hopkins University 

 Baltimore, Md. 



(With 6 Plates) 



INTRODUCTION 



In a previous paper (Rasetti, 194S) the writer described the Lower 

 Cambrian trilobites occurring in the conglomerate boulders of the 

 lower St. Lawrence valley, to the exclusion of the superfamily 

 rtychopariidea.^ The present paper completes the description of the 

 fossils of Early Cambrian age. The material in hand is exceptionally 

 well preserved in limestone, and its illustration may bring a contribu- 

 tion to the knowledge of this difficult group of trilobites. Most of the 

 specimens were collected by the writer during the summers of 1941 

 to 1946, in part with the aid of a grant from the Penrose Bequest of 

 the Geological Society of America. Some of the species were already 

 described on the basis of material collected by Walcott and preserved 

 in the U. S. National Museum. Fifteen species, nine of them new, 

 are described, and three new genera are established. In addition, six 

 new forms are described but left unnamed. All the type material was 

 deposited in the U. S. National Museum collections. 



OCCURRENCE AND AGE OF THE FOSSILS 



The fossils here described, as those illustrated in the previous paper 

 (Rasetti, 1948), were recovered from limestone boulders in presuma- 

 bly Lower Ordovician conglomerates (Rasetti, 1946) outcropping at 

 various localities on the south shore of the St. Lawrence River, from 

 Levis to Grosses Roches in Matane County. A list of the localities 



1 There is no generally accepted ending for trilobite superfamilics. The writer 

 successively used the endings -idea and -oidae. Until an agreement is reached 

 among trilobite students, it seems expedient to use the same ending as in the 1948 

 paper. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 128, NO. 7 



