700 THE PALEONTOLOGY OF MINNESOTA. 
; [Asaphus. 
Conrad’s Calymmene senaria* and Green’s C. blumenbachiy from Trenton Falls, N. 
Y., are distinct from C. callicephala, as shown by the accompanying figure of the 
cephalon of the latter, which indicates the decided genal spinules and the long 
shovel-shaped, not abruptly concave, anterior extension. The Cincinnati form may 
~ 
Diz 
Fig. 3.—Outlines of cephalon of Calymmene senaria Conrad, Trenton Falls, N. Y. 
also occur in the Trenton fauna of New York as it does in the Hudson River or 
Lorraine shales of that region, but the usual Trenton species must retain the name 
proposed for it by Conrad. 
Among the Minnesota specimens is one to which my attention has been especi- 
ally directed by Mr. Ulrich, from the Hudson River group near Spring Valley, 
bearing a cluster of coarse tubercles on each segment of the axis near the dorsal 
furrows. I am disposed to believe that the original size of these tubercles has been 
enlarged by a slight deposit of tufaceous matter upon them, but even if this 
supposition be correct the tubercles must have been larger than usual on this part 
of the test. The epidermal granulations are seldom well retained in the Ohio 
specimens but some of the Minnesota examples show them distinctly, while in the 
New York specimens they are clearly defined over the entire dorsal surface. 
Formation and locality.—Galena shales, St. Paul, Cannon Falls; Hudson River group, near Spring 
Valley, Minnesota. 
Family ASAPHID&. : 
Genus ASAPHUS, Brongniart, 1822. 
Subgenus ISOTELUS, DeKay, 1824. 
The original species of Asaphus, A. expansus Wahlenberg, is of a type which does 
not appear to be represented in the American faunas. Its lobate glabella, distinctly 
segmented pygidial axis, and narrow thoracic axis, are sufficiently distinctive to 
give the term a morphological value when thus restricted. DeKay’s term Isotelus, 
very significant and proposed two years later, includes species with broad axis and 
obsolete segmentation at maturity. We therefore believe that an excellent purpose 
*4th Ann, Rept. Pal. Dept.; N. Y. Geol. Survey, p. 49; 1841. 
+Op. cit., p. 28, cast 1, 
