O o o 



LEioK'Hvxcurs (2(Ai)i{H'()STATr.M. ( A'jiiiuxeiii. ) [Fly;. 14->.) 

 (Pal. X. Y.. Vol. IV.. p. :jr,7. PI. LVl. ) 



Distinguit<hiuu:Chanu-ters. — P>i-oa(lly ovate outline ; almost 

 smooth lateral slopes, the plications beinji* verv faint: small 



Fig. 14:3. Leiorhi/nchus qnadricostutnm. Two lirachial valves and out' pe'licl'' \alve, 

 natural size, all much distorted (fi-oni Halli. 



nnniber (three to five) of rounded ])lications on the fold and 

 sinas. This species is normal in the Genesee slate, but has 

 not been found in it in the region under discussion. S])eci- 

 mens approaching it in character, if not identical with it, 

 occur in the ui)per Moscow shale, at Section 1. 



LEioKHYXCHrs Li.MrrAKK. (Vanuxem.) (Fig. 144.) (Pal. 

 N. Y.. Vol. IV.,]). 356. PI. LVl.) 



DistinguLshiiig Chnrncters. — Ovate to sub-()rl)icular out- 

 line ; gibbous char- 

 acter of old uncom- 

 press e d speci mei is ; 

 mesial fold and sinus 

 b e c o m e develojied 

 near the front; numerous angular or sub-angular plications, 

 those of the fold and sinus bifurcating, those of the lateral 

 slo])es rarely dividing; fine concentric strife. 



Found in the lowest ten feet of the Transition shales, in 

 the Lake Shore sections; ui)i»er ^larcellus shales, in Bay 

 View Cliff. 



Leiorhynchus dibh m. Hall. I Fig. 145.) (Pal. X. Y., 

 Vol. IV., p. 364, PI. LMI. ) 



Difitinguishjug Characters. — OvRte outline, rapidly ex- 

 panding towards the front: moderate and almost e([ual 

 ccmvexity of valves; very faintly developed fold and sinus; 



Fig. 144. Leirirlu/nclms liinitare. Dor.sal, profile, and 

 front views of a small specimen (from Hall). 



