OF DENISON UNIVERSITY. 



75 



above the middle. Length 41 mm; height 35 mm. Free-stone of 

 upper Waverly. The hinge characters are unknown. 



Microdon reservatits, l^all. 

 (Plate IV, Fig. 14.) 



This species is common in the free-stone of middle Waverly, but 

 neither of our figures gives a typical form. Fig. 14 is abnormally ele- 

 vated behind. Fig 4 of Plate X, is a small variety with beaks more 

 central than usual. See Modiomorpha, below. 



A typical specimen is sub-quadrangular, i^^ as long as high, flat, 

 and finely marked concentrically. The lower margin is a very shal- 

 low elliptical curve ; postero-dorsal slope slightly inclined, nearly plane; 

 hinge line behind the beak nearly straight; posterior margin making 

 with it an angle of about 120°, very slightly curved, anterior margin 

 slightly concave forming an angle of nearly 140° with the hinge, an- 

 tero-inferior projection rather abruptly rounded. Hinge in our casts 

 showing only a shallow groove before and behind the beak. The 

 generic reference is unsatisfactory. 



Grajmnysia rhomhoides. Meek. 

 (Plate Vni, Fig. 12 ?) 



Typical specimens are frecjuent in the free-stone of middle Wa- 

 verly. (Our figure is from an unusual form which may rot repre- 

 sent this species. ) 



The relations of the associated form figured on Plate \\\ Fig. i, 

 are unknown. 



(JaniJUfj'^irt h(tiinihn1ensis. simm. 



This species is not very common in the free-stone of middle Wa- 

 verly. Certain forms of PaUv^oneilo elliptica are are frecpiently mis- 

 taken for it. Fig. 13, of Plate IV, is apparently a fragment of this 

 species. 



