PLATE XIX. 



(Figures 1-23 by R. P. Whitfield.) 



Legend, j. Cardinal [irocess. a'. Posteiioi- adductors. 



a(=g). Anterior adductors. v. Brachial ridges. 



(JKNUS PKODLXTUS, Soweuby. 



(See Plates XVIIa and XVIII.) 



Pago 321. 



Productus (Marginifera) splendens, Norwood :uh1 T^atteii [P. longispinnn, Sowerhy). 



Figs. 1, 2, 3. Three views of a specimen with a few ribs and scattered sjiine-bases, and a nacreous shell 

 texture. 



Upper Coal Measures. Wintcrset, Iowa. 

 Fig. 4. The interior of a brachial valve; showing the cardinal pi-ocess, muscular impressions and brachial 

 ridges. At la; is a row of .«hurt spinulos which project fi-om the inner surface of the shell, a 

 feature more highly developed here than in any other species observed. The submarginal 

 ridges which characterize Waagbn's subgenus Marginifeka are not highly developed in this 

 specimen. X 2. 



Coal Measures. Im 8alle, Illinois. 



Productus Nebrascensis, Owen (= P. aftpersus, McCliesney). 



Figs. 5, G, 7. Three views of a specimen ; showing the great abundance of short spines. 

 Coal Measures. La Salle, Illinois. 



Productus costatus, Sowerby. 



Fig. 8. The exterior of a pedicle-valve ; showing the general character of the specimens referred to this 



species in this country. 

 Figs. 9, 10. Profiles of two individuals of different size. 



Fig. 11. The inteiior of a brachial valve, with the muscular impressions and brachial ridges. 

 Fig. 12. An enlargement of the posterior face of the cardinal process ; showing its thickened base and trilo- 

 bate character. X 3. 

 Fig. 13. An internal ciist of the pedicle-valve; showing the diductor and adductor muscular scars. 

 Coal Measures Winterset, Iowa. 



Productus punctatus, Martin. 



Fig. 14. The interior of a brachial valve. 



Fig. 15. The cardinal jirocess of the same specimen, viewed from the posterior side. X 3. 



Fig. 16. The .same in profile. X 3. 



Coal 'Measures. Missouri. 



Figs. 17, 18. Two views of a pedicle-valve; showing the spiniferous bands which form concentric annulations. 

 Referred to this species with doubt. 



Coal Measures. Locality f 



Productus semireticulatus, Martin. 



Fig. 19. The central portion of a brachial valve, which retains with unusual distinctness the nuiscular and 

 brachial impres.sions. 



Fig. 20. Posterior view of the cardinal process ; .showing the complete coalescence of the iinier divisions of 



the two lateral lobes. X 3. 

 Fig. 21. The inner face of the same. X 3. 

 Fig. 22. The interior of a small brachial valve. 



Fig. 23. The interior of a pedicle-valve ; showing the adductor and diiluctor scars. 

 Coal Measures. Itaituha, Brazil. 



