E. Billings—New Species of Paleozoic Fossils. 353 
conglomerate which constitutes an important formation on the 
south shore of the St. Lawrence, below Quebec. The age of 
shell itself in some of the specimens is covered with fine longi- 
tudinal striw, from five to ten in the width of aline. The shell 
es obscure sub-imbricating rings of growth. 
His species has been found at Bie and St. Simon. : 
. "1g. 1 6, representing the transverse section, is not so dis- 
Col flattened on the ventral side as it is in most specimens. 
Collected by T.C mn. : 
_ 41. Americanus—Length from twelve to eighteen lines, 
tapering at the rate of about four lines to the inch. Section 
triangular, the three sides flat, slightly convex or slightly con- 
cave, the dorsal and lateral edges either quite sharp or epee 
roun Lower lip rounded, projecting about two lines in full- 
Am. Jour. Sc1.—Turrp Series, Vor. III, No. 17,—May, 1872. , 
23 
