FOSSILS OF THE CLINTON GROUP. 555 



curvature being sufficiently pronounced to be readily recognized ; some- 

 times the curvature is more marked but it never equals that of such 

 forms as Subulites ventricosa. The largest specimens were about 50 mm. 

 long; the length of the third whorl was 1.5 mm.; of the fourth, 2.5 mm.; 

 fifth, 3.5 mm.; sixth, 5 mm.; seventh, 7 mm.; eighth, 12.5 mm.; the 

 body whorl was not shown for its entire length^ but in another specimen 

 of about equal size it was 30 mm. long and 10 mm. broad. It is possible 

 that the measurements of this body whorl, as taken from another speci- 

 men, are slightly too small. The aperture was 18 mm. long and, as far as 

 one could judge from the outer broken lip of the shell, about 5 mm. wide 

 or possibly a little less. In the case of several specimens the shell sur- 

 face was well preserved, but it was perfectly smooth. The shell itself 

 was quite thick. 



This species is closely related to Subtilites terebriformis, Hall and 

 Whitfield, of which it is the precursor, and of which it may be regarded 

 as a variety. The Clinton form differs in having a much shorter body 

 whorl, which shows greater curvature on the side opposite the aperture • 

 the mouth is broader and more elongate-ovate. 



The moderate curvature shown by many of the specimens of this 

 species, suggests the origin of these forms from a still more curved form 

 while they themselves are precursors of the straight Guelph species, 

 Subulites terebriformis. Subulites attenuahis, Lindstrom is a still more 

 similar form. 



This species occurred in considerable abundance in the "Orthoceras 

 block," from the base of the Clinton at Huffman's Quarry, Ohio. 



Subulites {Polyphemopsis) plani-lateralis, sp. nov. 



{ Plate 37a, Figs. 4 a, b, c.) 



This species is represented by the single specimen used as the type, 

 belonging to Mr. Geo. Caswell, who informed the writer that he had him- 

 self cut the specimen out of a piece of Clinton limestone, from the Clin- 

 ton rock of the Soldiers' Home Quarry. It is now 8.2 mm. long, but has 

 lost its apical whorl which would have given the specimen a total length 

 of at least 8.5 mm. Its width was about 3 mm. There were 7 whorls in 

 the complete specimen. The mouth was 8.5 mm. long and perhaps about 

 1.7 mm. wide; above, towards the apical end of the shell, it was pointed; 

 at the opposite extremity it was rounded evenly; the inner lip of the shell 

 aperture was formed by the curvature of the outer lip around so as to 

 join the previous whorl on the inner side; it thus formed a moderately ele- 

 vated inner lip on the side opposite the outer lip, which became obsolete 

 on reaching the middle height of the aperture. The whorls present flat 

 sides, very moderately incurved near the line of meeting of successive 

 whorls, so as to form a very moderate groove there. The surface is 

 marked by straight, rather faint striae, which curve moderately at the 



