PALEONTOLOGY. 411 



GenusSPlRIFERA Sowerby. 



Spirifera Vauuxemi. 



Plate I, figs. 4 aud 5. 

 Orthis plicata Vanuxem, Geol. Rept. 3d Dist. N. Y., 1842, p. 112, fig. 1. 

 Spirt/era Vanuxemi Hall. 



The shells of this, species are abundantly scattered over the surface 

 of certain layers of the Waterlime rock, at Peach-Point, Put-in-Bay 

 Island ; associated with Leperditia alta of Conrad, and occur of all sizes 

 from those of not more than an eight of an inch in transverse diameter 

 to those of about five-eighths of an inch, and present all the features of 

 those of the Tentaculite limestone of eastern New York. The form is 

 transversely oval in outline and convex in profile, on each side; the 

 ventral being the most rotund; cardinal angles rounded and cardinal 

 line short; ventral beak strongly incurved. The shell is marked on 

 each side of the mesial fold or sinus by about four strong, rounded pli- 

 cations and are separated by concave spaces, which on the ventral valve 

 appear of about equal width with the plications, but on the dorsal are 

 narrower and somewhat sharper in the bottom. The mesial fold is fully 

 twice as wide as the strongest plication, is somewhat regularly rounded 

 or depressed convex, while the mesial sinus of the ventral valve appears 

 narrower and deeply concave. The surface of the shell is marked by 

 fine transverse or concentric striae which are strongly undulated in cross- 

 ing the plications and fold, and under a magnifier are seen to present 

 considerable regularity in size and arrangement. 



The species presents many similarities to S. crispus Hisinger; as it 

 occurs in the Niagara group of New York and other places in America, 

 as well as to those of European localities. In fact it is quite difficult to 

 see wherein they differ, but as the Lower Helderberg forms are nearly 

 always found only as separated valves and more or less exfoliated, there 

 is some difficulty in instituting satisfactory comparisons. 



Formation and Locality. — In hydraulic limestone of the Lower 

 Helderberg group, at Peach Point, Put-in-Bay, Lake Erie. 



Genus MERISTELLA Hall. 

 Meristella Icevis. 

 Plate I, figs. 6—7. 

 Airypa /avis Vanuxem, 1842, Geol. Rept. 3d Dist. N. Y., p. 120, fig, 2. 

 Merista Icevis (Vanux.) Hall, 10th Rep. State Cab., p. 94. 

 Merista (= Meristella) usvis (Vanux.) Hall, Pal. N. Y, vol. 3, p. 247, pi. 39, fig. 3. 



Shell below a medium size, longitudinally ovate in form, and very ventricose ; 

 ventral valve much longer than the dorsal, with a strong incurved beak, from which 

 the shell constantly widens to below the middle of the length; body of the valve 

 flattened along the centre in the upper part, and gradually becoming more and more 

 depressed until it becomes concave toward the front, forming a very distinct mesial 

 sinus- front slightlv prolonged and bent upward. Dorsal valve very convex in the 



