756 THE PALEONTOLOGY OF MINNESOTA. 
{Harpina minuesotensis. 
Surface deeply pitted over the free cheeks and marginal expansions. The 
puncte are circular, large, attaining their greatest size where the surface is most 
deeply concave. They appear not to be confluent at any place, but become obsolete 
on the marginal rim. 
The single specimen observed has an axial length of 124 mm.; length to end of 
cheek spine, 23 mm.; basal width 26 mm. 
It is hardly necessary to indicate the particulars in which this fossil differs from 
the described species of Harpes. The character of the ornamentation, the form of 
the glabella and its lobation, the absence of broad, lobate expansions about the basal 
angles of the glabella, the oblique direction of the ocular ridges, as well as the curve 
of the marginal outline, are all distinctive characters. 
Harpes is a genus which is not abundantly represented in species in any country, 
though its species are found from the Lower Silurian to the middle Devonian. It is 
a curious fact that all American species are from the Lower Silurian with the possi- 
ble exception of the HH. consuetus Billings, from the Island of Anticosti, which may 
belong to a middle Silurian, or a Hudson River-Clinton fauna. In Bohemia none_ 
of the forms described by Barrande are from the Lower Silurian but are distributed 
throughout the Upper Silurian and lower Devonian, while in Germany it ranges 
through the Devonian faunas disappearing with the fauna of Gonitatites intwmescens 
(Intumescens-kalk). . 
The late Dr. Ottomar Novak called attention* to the intermittent occurrence of 
Harpes in the faunas of the Bohemian basin. Two of the eleven known species 
appear early in the Lower Silurian (étage D,), but from that horizon to the étage Ez 
Fig. 77.—Hypostoma of Harpes venulosus Fig.78.—Hy postoma of Harpina prima, enlarged 
Corda, enlarged. ‘Etage F,). After Novak. (Etage D,.). After Novak. 
including five of Barrande’s stratigraphical divisions, there is no evidence of its 
existence. Novak, suspecting a structural difference between the Lower and Upper 
Silurian species, which is not apparent from the exterior except in a less number of 
*Studien an Hypostomen der bihm. Trilobiten, No. ii, p. 4, pl. 1, 1884. 
