PLATE XVII— Continned- 



Productella exanthemata, Hall. 



Fig. 17. The intei-ior of a brachial valve ; showing: the cardinal process. 

 Hamilton group. Tinker's Falls, N. T. 



Productella costatula, Hall. 



Figs. 18, 19, 20. Three view.? of a jiedicle-valve. 



Chemung group. Chemung county, N. T. 

 Fig. 35. The interior of a brachial valve. Above the figure is an enlargement of the cardinal process. 



Chemung group. Cattaraugus comity, iV. Y. 



Produgtella dumosa, Hall. 



Fig. 21. The extei'ior of a pedicle-valve, showing the j'ounded costie with numerous spine-bases. 

 Hamilton group. Canandaigua lake, N. Y. 



Peoductella lachrymosa, Conrad, var. lima, Conrad. 



Fig. 22. A view of the pedicle-valve. 



Fig. 23. A pedicle-valve with somewhat more elliptical outline. 



Chemung group. Cattaraugus county, N. Y. 



Produgtella Boydi, Hall. 



Fig. 24. A pedicle-valve retaining the spines on the cardinal extremities. 



Chemung group. Near (Philipshurgli) Belmont, N. Y. 



Produgtella spegiosa. Hall. 



Figs. 25, 26. Two views of tlie pedicle-valve ; showing the closely-arranged spine-bases. 

 Chemung group. Chautauqua county, N. Y. 



Produgtella striatula, Hall. 



Fig. 27. The exterior of a pedicle-valve. 



Fig. 38. Cardinal view of an internal cast of the pedicle-valve ; showing- the mucular scars. 



Fig. 44. An enlargement of the external surface of the shell. 



Chemung group. Chautauqua county, N. Y. 



Produgtella hirsuta. Hall. 



Fig. 28. A pedicle-valve, retaining spines neai' the cai-dinal margin. 



Fig. 39. An enlargement of the cardinal jirocess ; showing the divergence of the lobes and the edge of the 



grooves on their postei'inr face. 

 Fig. 45. An enlargement of the external surface. 



Chemung group. Meadville, Pennsylvania. 



Produgtella hystricula. Hall. 



Fig 29. The interior of the brachial valve ; showing the cardinal process and the dental sockets. X 2. 

 Fig. 30. The exterior of the pedicle-valve ; showing the fine, closely crowded spines. 

 Chemung group. Chatauqua county, iV. Y. 



Produgtella arcuata, Hall. 



Figs. 31, 32. Two views of a pedicle-valve. 



Yellow sandstones. Burlington, Iowa. 



Produgtella rarispina, Hall. 



Fig. 33. A pedicle-valve with a few scattered spines. 



Chemung group. Alleghany county, N. Y. 



