Contributions to Invertebrate Palseontology. 619 



Crania carbonaria Whitf. Page 599. 



Fig. n. View of a valve of ScMzodus ampins Meek and Worthen, bearing a 



number of attacbed valves of tbis species. 

 Fig. 12. Anotber lower valve parasitic on tbe operculum of Naticopsis altonensis 



var. giganteus M. and W. 



Macrocheilds regularis Cox. Page 600. 

 Fig. 13. Front view of a specimen from Carbon Hill, Obio. 



LoxoNEMA PLicATUM Wbitf. Page 601. 



Fig. 14. Lateral view of a specimen, natural size. 

 Fig. 15. View of ibe last volution enlarged. 



Nautilus (Gyroceras ?) subquadrangularis Wbitf. Page 602. 



Fig. 16. Lateral view of the specimen showing the features of the species as 

 far as known. 



PLATE XVI. 



The figures on the upper half of the plate illustrate the fauna of the Coal Measure 

 Cherts of Hocking County, Ohio. 



DisciNA Meekana Wbitf. Page 603. 



Fig. 1. View of a lower valve from the black chert beds. 

 Fig. 2. View of a more nearly entire valve from Flint Ridge. See lower left 

 corner of plate. 



Spirifera (Martinia) lineata Martin. Page 603. 



Figs. 3, 4, and 5. Dorsal, ventral, and front views of an internal cast from 



the yellow cherts. 

 Fig. 6. View, enlarged to two diameters, of a partial cast from the black 



chert. The specimen shows the setae where tbe shell is retained. 



Athyris subtilita Hall. Page 604. 

 Figs. 7-9. Dorsal, ventral, and profile views of an internal cast of this species. 



AvicuLOPECTEN iNTERi.iNEATus M. and W. Page 604. 



Figs. 10 and 11. Views of an imperfect left and right valves as obtained by 

 gutta-percha from the casts in the yellow cherts. 



Natica Ortoni Whitf. Page 605. 



Figs. 12 and 13. Front and back views, enlarged to two diameters, of a speci- 

 men from the yellow cherts. 



Fig. 14. Diagram of the aperture as shown by the breaking of the shell back 

 of the aperture, showing tbe thickened shell. 



