THE OTTAWA NATURALIST 



VOL. XXII. OTTAWA, SEPTEMBER, 1908 No. 6. 



NOTES ON THE PELECYPODA OR BIVALVE MOL- 



LUSCA OF THE CHAZY FORMATION IN CANADA, 



WITH DESCRIPTIONS OF ONE NEW GENUS 



AND FOUR NEW SPECIES FROM THE 



CHAZY SANDSTONE AT THE HOG'S 



BACK, NEAR OTTAWA. 



By J. F. White.wes. 



All bivalve mollusca, whether fossil or recent, such as 

 clams, mussels, oysters, and the like, belong to a class for which 

 various names haA^e been proposed by systematists. Among 

 these names some of the best known are AWupa, Aristotle ; 

 Bivalvia, Linnaeus (1767); Acephala, Cuvier (1798); Lamelli- 

 branchiata, Blainville (1816); Conchifera, Lamarck (1818), 

 and Pelecypoda, Goldfuss (1821). For many years the name 

 Lamellibranchiata has been in use for this class, but Pelecypoda 

 is the one now preferred for it by some of the latest authorities, 

 on account of its uniformity with other molluscan class names, 

 such as Gasteropoda, Scaphopoda, and Cephalopoda. 



The pelecypoda of the Chazy .formation in Canada have 

 not been studied at all exhaustively, and not many of the 

 species that occur therein have been either determined or 

 described. 



In the late Mr. E. Billings' excellent paper on the "Fossils 

 of the Chazy Limestone," which was published in the "Canadian 

 Naturalist and Geologist" for December, 1859, about tw^o pages 

 are devoted to the consideration of the pelecypoda of that 

 formation, under the name lamellibranchiata. Fossils belonging 

 to this class, Mr. Billings writes, are "rare in the Chazy lime- 

 stone, yet the species appear to be somewhat numerous. I 

 think I can make out 17 species belonging to Ctenodonta, Cyrto- 

 doita, Vauuxemia, Modiolopsis, and probably two or three 

 other genera. As the specimens consist mostly of casts, they 



