PLATE XXVII. * 



PAGE 



Pig. 1. Myalina svvallovi, McC 341 



1. Side view. 



1 a. Dorsal view of an internal cast. 



1 b. Dorsal view of another specimen. 



\ c. Side view of same. 



1 d. Surface striae of same. 



Fig. 2. Pleurophorus subcostatus, M. and W 347 



2. Side view of an internal east, showing the muscular and pallial impres- 



sions, as well as the impression of the long posterior hinge tooth. 



2 a. Dorsal view of the same. 



Fig. 3. Myalina meliniformis, M. and W 343 



Side view of an internal cast, showing muscular and pallial impressions. 



Fig. 4-5. Aviculopecten occidentalis, Shum ? 331 



4. Internal cast of a right valve, showing the muscular scar, deep byssal 



sinus, and the impression of the cardinal area. 



5. Internal cast of left valve. (Costas not well represented in engraving.) 



5 a. Surface marking of left valve slightly enlarged. 



Fig. 6. Edmondia unioniformis, Phillips? 34G 



6. Dorsal view. Of an internal cast. 



6 a. Dorsal view of a left valve of another specimen, showing the impres- 



sion of the cartilage attachment. 

 6 b. Side view of same. 



Fig. 7. Schizodus , (Sp?) 345 



Side view of an imperfect internal cast. 



Fig. 8. Turritella? Stevensana, M. and W 382 



8. Side view enlarged. (Natural size shown by the line at its side.) 



8 a. Body and succeeding whorl, considerably enlarged, to show the sur- 



face markings. 



Fig. 9. Allorisma, (Sp. undt.) , 350 



9. Dorsal view of internal cast. 



9 a. Side view of same. 



Fig. 10. Macrochejlus, (undt.) 372 



View of internal cast. 



Fig. 11. Pterinea (Monopteria) gibbosa, M. and W 340 



11. View of internal cast left valve. 



11a. Anterior view of internal cast of right valve, showing the lunle. 



11 b. Side view of the last. 



at 



Fig. 12-14. EumicrotiiTHawni var. sinuata, M. and W 338 



12. Anterior view of internal cast of a left valve. 



12 a. Side view of same, showing the sinuous anterior margin. 

 12 6. Surface markings of left valve. 



13. Internal cast of a right valve, showing the deep byssal sinus and mus- 



cular scar; also, the beak of the left valve rising above, with the 

 cast of the cartilage pit beneath it. 



14. A cast of another left valve, differing somewhat in form from fig. 12a, 



• The fossils fl^nred on this plate are placed together, because they are all associated in a bed once 

 * opposed to he probably of Permian age. 



* <?^u^trvwCnA^ 



