336 Lower Silurian Fauna of Minnesota. 



margin, and marked often by a groove made by the penultimate volu- 

 tion, below the false beek. The figures are of a siliceous cast of a 

 specimen somewhat under medium size. Good specimens are rare. 

 From the Stictopora bed at Minneapolis and in Goodhue county. 



CARiNAROPSis (or bellerophon) phalera n. sp. 

 Plate VI, figures 14, 15, and 16. 

 Shell of about two whorls in the same place; — the last one ex- 

 pands so rapidly as to give a patelliform outline. About one and one- 

 half volutions exposed. Casts show indistinct radiating folds on the 

 dorsal surface; crossed by concentric undulations (on one specimen). 

 Dorsally and laterally subangulated, but only the dorsal carina contin- 

 ues to the margin of the aperture. Ventral surface grooved. Aperture 

 circular, diameter 3 cm., truncated or emarginated anteriorly. Rare. 

 From the Stictopora bed at Saint Paul. 



coNCHOPELTis (or metoptoma) obtusa n. sp. 

 Plate VI, figure 17. 



Compare C. minnesotensis Walcott, 



Shell large, patelliform, or subconical, apex eccentric, apical angle 

 no degrees. Aperture subcircular, about three times as wide as the 

 shell is high. Cast marked by four or five concentric furrows and by 

 numerous elevated radiating lines, from 15 to 20 in one centimeter. 

 Rare. From the Stictopora bed at Minneapolis. 



FUSISPIRA ( ?) SPICULA n. sp. 



Plate VI, figures 10 and 11. 



Of this shell only one imperfect interior cast is known. This shows 

 that the apical angle was about 12 degrees ; sutures probably not vis- 

 ible on the exterior of the shell ; transversely marked by fine lines that 

 run obliquely back ; aperture subquadrate, oblique, narrowest next the 

 suture; shell delicate. 



Found by Prof C. W. Hall in the Trenton shales (in the Stictopora 

 bed) at Minneapolis. 



holopea(?) perundosa n. sp. 

 Plate VI, figures 12 and 13. 



Shell large, coiled into two or three rapidly enlarging volutions. 

 Apical angle 180°. Suture deep. Umbilicus large. Casts of interiors 

 only known. These are transversely marked by fine growth lines; and 

 by large nodulose undulations on the upper and outer surface, that are 

 continuous with or alternate with like undulations on the lower surface. 

 A transverse section, parallel to the above mentioned markings, is oval 

 with the apex at the outer lower margin. 



This species agrees with H. pyrene Billings, so far as known, in 

 every respect except that the latter is described as having an elevated 

 spire which this species has not. Rare. 



Found in the Orthisina bed at Kenyon, Goodhue county, Minn. 



