PLATE LXXIV. 



(Figures 1-9 by R. P. WHiTriELD.l 



Gknos AMPHIGENIA, Hall. 



Page 252. 

 See Plate 73. 



Amphigenia elongata. Viinii.xciii. 



Fig. 1. Dorsal view of a pai-tial cast; showing- the muscular inijiressions and \-ascular sinuses of the 

 brachial valve, and the cavity left by the medially tlivided hing-e-plate. 

 Coniiferous limestone. Clarence, New York. 

 Fig. 2. Cardinal view of an intenial cast : showing the filling of the sj)Ondylium and of the visceral fora- 

 men, and the cavities left by the median septum and hinge-plate. 

 Fig. 3. Median longitudinal section of both \-alves ; showing the degree of development of the .spondy- 

 lium, median septum, and septal plates ; also the great thickness of the shell in the umbonal 

 region of the brachial valve and the length of the crura, with their convex terminal expansion. 

 Corniferous limestone. Le Hoy, New York. 

 Fig. 4. Dorsal view of an individual of medium size with regularly elliptical form and tinely striated 



surface. 

 Fig. 5. An internal cast of the unil>oual portion of the brachial valve; showing the septal plates, the four 

 sharjily defined scars of the adductor muscles, the \ascular sinuses and genital markings. 

 Corniferous limestone. lVe,<itern New York. 

 Fig. 6. The exterior of a brachial valve having the characteristic subovate outline. 



Figs. 7, 9. Dorsal and profile views of a shell of full medium size with giblious valves and finely striated 

 sui'face. 



Corniferous limestone. Cayuga, Ontario. 

 Fig. 8. Internal cast of a large brachial valve ; showing the muscular impression and the cavity left by 

 the removal of the hinge-plate. 



Corniferous limestone. Le Hoy. Ne%c York. 



