

216 



Foinid in the Eliicrinal limestone, at Section 5 ; the Sticto- 

 pora and Demisaa beds, at Section 5 (abundant) ; shales be- 

 low the Trilobite beds, in Avery's Ravine (rather common) ; 

 Pleurodictyum and Calcareous beds above (very rare). 



Spirifer (Martinia) subumbonus. Hall. (Fig. 124.) 

 (Pal. N. Y., Vol. IV., p. 231:, PI. XXXII.) 



DistinguishingChaTacters.— XevyHnmWHize (for a Spirifer) ; 

 ■y , . . „ , . gibbous character; rounded 



'^ ' ■' cardinal ex ti-emi ties; 



smooth or concentrically- 

 striated surface; highcardi- 



FiG. 124. Spirifer stibumbomis. Dorsal and . 



profile views of a specimen, enlarged: en- nal area lU pcdlClC Valve, 

 largement of the surface to show the pits ^ 



(after Hall). witli rouudcd margins; ab- 



ruptly incurved beak of pedicle valve; narrow, almost obso- 

 lete, and never pronounced, sinus; absence of fold, an im- 

 pressed line occasionally marking the center of the brachial 

 valve; in well-preserved and partly exfoliated specimens 

 numerous punctie or pits appear, probably marking the 

 former position of spines. 



Found in the Styliolina band, at Section 1; Moscow 

 shale (uppei' four feet), at Sections 2, •), 4 (rare) ; Hamilton 

 shales, about two feet below the Encrinal limestone, at Sec- 

 tion 6 (one specimen); also in the shale between the Nauti- 

 lus and Stroi)halosia beds, in Avery's Creek. 



Gknis AMBOCCELIA. Hall. 



[Ety. : Ambon, umbo; koilox, belly.] 



(1860: 13th Ann. Rep't N. Y. State Cab. Nat. Hist., p. 167. 

 1893: Pal. N. Y., Vol. VIII., Pt. II., p. 54.) 



Shell of small size; piano-, concavo-, or gently bi-con vex, 

 the pedicle valve always deepest, and commonly extremely 

 convex, with a strongly marked, arched and incurved umbo. 

 A narrow median groove, moi-e or less profound, is commonly 

 present. The cardinal area is arched, its margins are well 

 defined, and it is divided by an open delthyrium, with incom- 

 plete deltidial plates. Strong articulating teeth, and a 



