Raymond: Gastropoda of the Chazy Formation. 199 



Family Euomphalid^e de Koninck. 



Genus Maclurites Lesueur. 



Maclurites magnus Lesueur. 



(Plate L, figures i, 2 ; Plate LI ; Plate LI I.) 



Maclurile magna Lesueur, 1818, Journal of the Academy of Natural 

 Sciences, Philadelphia, Vol. I, p. 312, PI. 13, figs. 1, 2, 3. 



Maclurea magna Emmons, 1842, Final Report of the Second District 

 of New York State Survey, p. 276, fig. 1. 



Maclurea magna Hall, 1847, Paleontology of New York, Vol. I, p. 

 26, PL 5, figs, \a-\d\ PL 5 fa's, figs. la-ic. 



Straparollus magnus Emmons, 1855, American Geology, p. 156, PL 



4, fig- 15- 

 Maclurea magna Raymond, 1902, Bulletin of American Paleontology, 



Vol. Ill, p. 305, PL 18, fig. 10. 

 Maclurites magnus Clarke and Ruedemann, 1903, Bulletin of the New 



York State Museum, No. 65, p. 542. 



This species was one of the first of American Paleozoic fossils to be 

 described. It has always been considered the characteristic fossil of 

 the Chazy, and as such has become widely known. It is not, how- 

 ever, by any means as widely distributed as it has been reported to be, 

 and it has constantly been confused with Maclurites logani Salter, 

 Maclurites bigsbyi Hall, and other species of the younger formations, 

 not so much because of its similarity as because of the familiarity of 

 the name Maclurea magna. From this fossil the Chazy has been 

 called the Maclurea Limestone. Maclurites magnus is a very common 

 fossil in the Chazy from Orwell, Vermont, north to Montreal, but it 

 should be pointed out that the Beekmantown formation contains more 

 species and probably as many individuals of this genus as the Chazy,' 

 and that the Stones River and Trenton also afford numerous shells of 

 the same genus, with more or less modification of form. 



Maclurites magnus is distinguished from Maclurites logani by the 

 more gradual increase in the size of the whorls and by the operculum, 

 which is horn-shaped in Maclurites magnus and oval in Maclurites 

 logani. The various Beekmantown species described by Billings, 

 have in general more numerous and more rounded whorls, although 

 there are exceptions. 



The following is Lesueur' s description : 



