235 



dowinvar(l to fill the sinuosity in the front of the pedicle 

 valve; fine concentric surface stria- and almost obsolete 

 faint radiating striae. 



Fonnd in the npper layers of the Encrinal limestone, at 

 Section 5, in Eighteen Mile Creek (rather common). 



Gi: xus TRIGERIA. Bayle. 



(1875: Explic. Carte Geol. de France, Atlas, PI. XIII. 1898: Pal. N. Y., 

 Vol. VIII., Pt. II., p. 273.) 



"Plicated centronellids with plano-convex valves. In the 

 ])rachial valve the hinge plate is tri])artite, the median 

 division being perforated by a visceral foramen. Brachidium 

 as in Centronella, though with a snmller anterior i)late." 

 ( Hall and Clarke. Hand-book Brach., Bt. H., p. 108. ) 



Trigeria (?) LEPiDA. Hall. (Fig. 14GA.) (Pal. N. Y., 

 Vol. lY., p. 27G, PI. XLY.) 



Distinguishiuti; Character><.— ^m?i\\ size; sub-equally con- 

 vex valves: much elevated beak of i)edicle valve; elongate 



''^ili'^ii^ 



Fig. 146A. Trigeria lepida. Ventral view of a specimen, natural size. Dorsal, ven- 

 tral, and profile views of a specimen, enlarged, x 2. Dorsal view of an individual with 

 unusually strongly marked sinus (from Hall ). 



oval opening, communicating with foramen above, and 

 fianked below by two convex deltidial plates; simple regular 

 surface plications, gradually enlarging towards the margins 

 of the valves; shallow sinus on brachial valve, formed l)y 

 depression of two or three central plications. 



Genus CRYPTONELLA. Hall. 



[Ety. : Signifying a small cavity.] 



(1861: 14th Annual Rep't, X. Y. State Cab. Nat. Hist., p. 102. 1893: Pal. 

 X. Y., Vol. VIII., Pt. II., p. 286.) 



Shell terebratuloid, with the valves of somewhat similar 

 convexity. Beak of pedicle valve erect or slightly inctu'ved 



