32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 128 



niculation at midwidth ; distal portion turned downward and forward. 

 Anterior facial sutures strongly convergent in front of eyes, widely 

 rounding off anterior cranidial outline ; posterior branch straight, 

 showing little change in direction from anterior branch in dorsal view. 

 Surface of test covered with granules of various sizes. Length of 

 largest (holotype) cranidium 8 mm. 



Remarks. — Upon examination of the material in the U. S. National 

 Museum, it appears that the cranidium which Resser singled out as 

 the type of Rimoitskia spinosa does not differ specifically from R. 

 typica. The smaller cranidia seem to possess, on the average, a more 

 pronounced and almost horizontal occipital spine, whereas in the larger 

 cranidia the spine is relatively smaller and almost vertically directed. 

 There is variability in this respect even among cranidia of the same 

 size. The other presumed differential characters are even less valid. 



Occurrence. — Known only from conglomerate boulders at Bic. 

 Association with olenellid fragments is conclusive proof of the Early 

 Cambrian age of the species. 



Ty/'^.y.— Holotype and paratype: U.S.N.M. No. 64998. Holotype 

 of Rimouskia spinosa: U.S.N.M. No. 94748. 



REFERENCES 



Howell, B. F., et al. 



1947. Terminology for describing Cambrian trilobites. Journ. Paleont., vol. 

 21, pp. 72-76. 

 LocHMAN, Christina. 



1947. Analysis and revision of eleven Lower Cambrian trilobite genera. 



Joum. Paleont., vol. 21, pp. 59-71. 



1948. New Cambrian trilobite genera from northwest Sonora, Mexico. 



Journ. Paleont., vol. 22, pp. 451-464. 

 1952. Trilobites. In Cooper, G. A., et al., Cambrian stratigraphy and 

 paleontology near Caborca, northwestern Sonora, Mexico. Smith- 

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 PouLSEN, Christian. 



1927. The Cambrian, Ozarkian and Canadian faunas of northwest Green- 

 land. Medd. Gr^nland, vol. 70, pp. 237-343. 

 1932. The Lower Cambrian faunas of east Greenland. Medd. Gr^nland, 

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 Rasetti, Franco. 



1945a. Faunes cambriennes des conglomerats de la "formation de Sillery." 



Naturaliste Canadien, vol. 72, pp. 53-67. 

 1945b. Fossiliferous horizons in the "Sillery formation" near Levis, Quebec. 



Amer. Journ. Sci., vol. 243, pp. 305-319- 

 1946. Cambrian and early Ordovician stratigraphy of the lower St. Lawrence 



valley. Bull. Geol. Soc. Amer., vol. 57, pp. 687-706. 

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