The Saint Peter Sandstone. 75 



they are exactly like H. obliqua Hall with the lower part broken off. In 

 vertical sections of H. obliqua Hall from the Stictopora bed of the Trenton 

 in Minnesota, the umbilicus was found to extend through the last or last 

 two volutions only. There seems to be nothing that indicates a distinction 

 between these specimens and H. obliqua as found in the Trenton of 

 Minnesota. 



South Saint Paul. 



Holopen paludiniformis Hall. 



Holopea paludiniformis Hall 1847. Pal.N. Y., vol. l,p. 171,pl.37,fig.3. 



One specimen indentical with the upper volutions of H. paludiniformis 

 is imperfect but differs in no way that can be seen, from specimens that 

 occur in the " Lower Blue Bed " of the Trenton limestone at Minneapolis. 



Found at South Saint Paul. 



Genus Murchisonia. 



Murchisonia cf. gracilis Hall. 



Plate III, figure 4. 



Murchisonia gracilis Hall, 1847. Pal. N. Y., vol.i, p. 181, pi. 39, fig. 4. 

 Murchisonia gracilis Salter, 1859. Can. Org. Rem., Decade I, pi. 5, tig. 1. 

 Murchisonia gracilis ? Whitfield, 1882. Geo. Wis., vol. iv,pl. 5, fig. 19. 



Several imperfect specimens have been found that approach M. gracilis 

 Hall, but that have the whorls less oblique, and also were much larger 

 when perfect than those in the Trenton and Hudson series of Wisconsin and 

 Minnesota. The specimen figured here has been distorted so that the 

 whorls appear too little oblique and the spire too broad. Other specimens 

 show that there were four or five more volutions below and there must 

 have been as many more to form the upper part of the spire. They resem- 

 ble in every way the figure of M. gracilis (Hall) Salter, from the Chazy or 

 Black River limestone at Paquette's Rapids, Canada. But this is larger, 

 with more numerous whorls and a greater apical angle than those of the 

 Trenton of Wisconsin and Minnesota, and it seems to differ in the same 

 way from Hall's figures of Trenton specimens from New York. 



Murchisonia cf. tricarinata Hall. 



A specimen probably belonging to this species was found at Highland 

 Park and was identified by me, but was afterwards destroyed accidentally 

 so that more exact comparison with the typical Trenton species is no longer 

 possible. 



Genus Opiiileta. 



Ophileta fausta, n. sp. 



Plate III, figures 8 and 9 



Coil of about three volutions nearly jn the same plane; spire concave, 

 the sides forming an angle of about 45°. The umbilicus is difficult to dis- 



