218 



Geologist and Palaeontologist foi- 1896. Faunas of tiu- 



Hamilton Group, etc., p. 27().) 



Distinguishing Cluiracters. — Small size; transverse outline, 



the pedicle valve being much broader than long; convex 



brachial valve, usually bear- 

 ing a shallow depression 

 along the center; numerous 

 elongated pits covering the 

 surface, showing spine bases 

 if a characteristic specimen, in well-i)reserved specimcns. 



ilus bed, enlarged (after Gra- ^ ^ 



Found in the Nautilus bed 

 at the base of the Hamilton shales, on the Lake Shoi-e and in 

 Avery's Creek (abutidant); Strophalosia bed, on the Lnke 

 Shore (very rare). 



A.Mnoc<ELiA PK.^crMBoxA. Hall. (Fig. 127.) (Pal. X. Y., 

 Vol. IV., p. 2(i2, PI. XLIV.) 



Distinguishing ClmrRcters. — Lar^^e size; sub-globose char- 

 acter; short hinge line; length greater than width: ventri- 



FiG. 126. Amhocxelia nana. Cardinal and 

 dorsal views of 

 from the Nautilus 

 ban). 



Fig. 127. Amboccelia pranimbona. Two brachial valves; pedicle valve and profile of 

 same (from Hall). 



cose pedicle valve, with narrow depression along center; 

 moderately convex brachial valve, occasionally bearing a 

 median depressed line. 



Found in the upper Moscow shale down to four feet from 

 the top, at Sections 1 to 5 (abundant). 



Amboc(ELI.\ spixosa. Clarke. (Fig. 128.) (13tli Ann. 

 Rep't State Geol. X. Y., Vol. L, p. 177, PI. IV.) 



Distinguishing Charm-ters. — Rather large size; hinge line 

 equal to width of shell ; brachial valve concave antei-iorly, 

 with upturned margins; low median elevation, indistinct 

 and disappearing towards the front; elongate surface pits, 

 probably nmrking positions of spinules. 



