I'LATK IV K— (jDiilinuciL 

 LlNtJlLA LAMELI-ATA, Hull. 



Fig. 10. View from thi- peiliclw-valve of an inU-nml cast. I'etaiiiiiijj the iini)ies.siim of the lateral and central 

 musrular .«cars ami of the pallial sinuses. The matiix is tilleii with minute ovoid Ijodies {»va), 

 which apjiear to be distril)nted wherevei' the sinuses and llieir branches have extended. Aliout 

 the anterior and lateral martrins of the valve the matrix is the opaque mud of the sediment ; 

 elsewhere the spaces l)etween the ova are translucent. X 3. 



Fig. II. The opjio-^ite side of the same specimen; also showing the muscidar, vasscular and se]>tal impres- 

 sions. Tlie intermixture of the opaque matrix on this side is somewhat greater than on the 

 other, obliterating the ova to some extent. X 3. 



Fig. 12. A tliin section of a portion of tliis specimen, which shows the ovoid t>odies to be ojiaipie and 

 homogenous. X 12 



Fig. 13. An enlargement of the surface of the cast ; showing the ai)i>earauce of the ova when magnilied 12 

 diametei's. The vertical ridges are c.a.sts of raiiiating furrows on the intei-ior of the valve. 

 Niagara group. Near HamiUvn, Ontario. 



LINGUL0P8, Hall. 



Pajrc IS 

 LlNGULOPS GrANTI, .sp. llov. 

 Fig. 14. The interior of a brachial valve. X 6. 



Fig. 15. The interior of a pedicle-valve. The muscular area is here ilevelojied into a well-detined plat- 

 form, while in the other species of tin' genus, L. Wh'itfieldi and L. Noi^woodi, it still retains its 

 linguloid character. X 6. 



Niagara group. Harniltcm, Ontario. 



CONOTRETA, Walcott. 



P.agc- 1114. 

 Conotketa KUSTI, W'lllcott. 



Fig. Iti. Anterior view of a pedicle-valve. The apical and anterioi- regions retain a portion of the shell, 



but elsewhere the .shell is removed, showing the impressions of the internal radiating muscular 



lidges. X 4. 

 Fig. 17. An internal cast of a smaller pedicle-valve ; showing tlie iilipression of the .strong ai>ical callosity, 



and the radiating ridges. X 8. 

 Fig. IS. An apical view of the .same valve ; showing the subtriangular posterior slope, and its otiscurely 



defined median furiow. X 9. 

 Fig. Ifl. Car<linal view of a very young individual, in wliich the postei-ior slope is very fainf. X 1-'. 



Ti-enton limestone. Trcnfmi Falls, N. Y. 

 Fig. 21'. Cardinal view of another very small example, retaining the sliell. 

 Fig. 21. Profile of same. X 2.5 



Hudson River group. Covington^ Ky. 



OBOLUS, ElCHWALD. 



I'age SO. 



Orolus [?J ruLCHEK, Matthew. 



Fig. 22. The exieiior of a valve, retaining the shell and showing the character of its oi-namentation. X 3. 

 SI. .John group. Caton's Island. Nno Brunswick. 



DISCINA, Lamakck. 



Page 120. 



DisciNA 8TKIATA, Sclimiwiclu'r. 

 Fig. 23. The interior of a pedicle-valve. 

 Fit: 2). The exterior of a similar valve. Much enlarged. 

 Recent. Cape Palmas. 

 (After Davidson. Trans. Linnean Soc.Ser. 2, Zool., vol. iv, jil. 2;'), figs. 24, 2,'). 18S0.) 



