42 Bulletin 9 334 



mens by having 10 or 15 costse and by its much smaller size. Yet 

 there seem to be intermediate stages, and for the present it will 

 be assumed that environment has caused the difference in the ap- 

 pearance of the two forms. 



Localities ( of this type ). — Alabama : Hatchetigbee Bluff; 

 4 miles above Hamilton Bluff, Alabama River; 

 Ozark, R. R. cut just below the Buhrstone. 



ANOMIA. 

 Anomia, sp. , Pl. 6, fig. 10. 



Two very young specimens of this genus, one of which is here- 

 with figured, were found at Hatchetigbee bluff. It seems inad- 

 visable to attempt a specific characterization of such immature 

 forms. However, one feature deserves special attention, viz, the 

 peculiar grooves converging posterior to the muscular impressions 

 and terminating in circular shallow depressions or pits. See 

 figure. 



Spondylus, sp. Pl. 6, fig. 11. 



Syn. Plagiostoma diimosmn Con., Foss. Sh. Tert. Form, 1835, p. 34. 



Spondylus dumos us. Aid., Amer. Jour. Sci., 3rd ser., vol. 30, p. 305, 



1885. 



Spondylns dumosus var. Aid., Bull, i, Geol. Surv. Ala., p. 50, 1886. 



We feel great hesitation in placing this upper lyignitic form in 

 with Morton's P. dumosum. For his description ( Synop. Org. 

 Rem. Cret. G'p.,p. 59, 1834) argees exactly with well preserved 

 specimens from Chickasawhay and other Vicksburgian localities, 

 but it does not agree so well with the specimens now under con- 

 sideration. Morton very properly remarks that dumosum has 

 spines on both valves. Our specimen figured has none. An- 

 other smaller specimen of a right valve does show spines, but 

 they are much finer and aciculate, the spine-bearing and inter- 

 mediate costse are more numerous than in dumosus. Again, 

 the valves appear more oblique. 



This subje6l will be discussed more fully in a future work on 

 the Vicksburg stage. 



Localities. — Alabama : Hatchetigbee Bluff ; Ozark, R. R. cut 



just beneath the Buhrstone. 

 Specimen figured. — From Hatchetigbee Bluff, in Cornell Uni- 

 versity colledlion. 



