FOSSILS OF THE CLINTON GROUP. 557 



width, but the third from the last, which is probably the second one of 

 the spire, is very much narrower, producing an effect very much like 

 that of small varieties of Pupa.. But if the lip of our shell be all the 

 shell ever possessed, then it will be noticed that its margin is not turned 

 outwards, but remains perfectly simple and thin along the outer lip, 

 while bending inwards slightly along that part of its margin usually 

 called the inner lip. The aperture is oval or almost round. The surface 

 of the shell is perfectly smooth. The height of the fourth whorl was 1.9 

 mm., of the third 1.4 mm., of the second .7 mm., and of the first con- 

 siderably less, as well as measurements could be made out in one speci- 

 men ; the width of the fourth whorl was 3 mm., and of the third whorl 

 2.6 mm. In the cast, the fourth whorl was 1.7 mm. long, the third 1.3 

 mm., the second .25 mm.; the width of the fourth whorl being 2.2 mm., 

 the third whorl about 2 mm., the second 1 mm. 



Whether there be any real genetic relationship between Paleopupa 

 and the later fresh water forms belonging to the old genus Pupa, it is 

 difficult to tell, though the general form of the shell might suggest that 

 conclusion. The specimens described were obtained in the " Orthoceras 

 block" at the base of the Clinton, Huffman's Quarry, which was filled 

 with a great variety of well known Clinton forms, none of which sug- 

 gested a fresh water origin, so that the fresh water nature of our shell 

 cannot be asserted. For the present, therefore, the generic name must 

 indicate an old form of the same general appearance as Pupa, rather than 

 the existenceof a genetic connection with the latter genus. Its posses- 

 sion of a sinistral spire might be emphasized. 



Pterinea brisa, Hall. 



(Plate 25, Figs. 14 a, b; Plaia 27, Fig. 30.) 



Pterinea brisa, Hall, is probably identical with Pterinea siricecostata. 

 McChesney, and the latter name should have precedence. In Ohio the 

 species is very common at Brown's Quarry; very few specimens have 

 been found in the limestone at Soldiers' Home; a single specimen was 

 found in the upper shaly courses at Huffman's Quarry; very typical 

 specimens occur at Todd's Fork. The species is too well known, and is 

 well enough indicated by the accompanying figure, to require detailed 

 description. 



The anterior wing is sinuate at its junction with the body, this 

 sinuosity giving rise to a concave area between the wing and the body i 

 towards the margin. The wing is quite convex, excepting at the hinge 

 margin where it is moderately concave before the beak. From the beak 

 radiate striae traverse the entire surface of the shell, and concentric 

 striae cross these. Sometimes both are equally developed, at other times 

 the concentric striae are more distant, being less like striae but rather re- 

 sembling lamellose layers ending at the surface of the shell. The shell is 



