Maryland Geological Survey 571 



Collections. — Maryland Geological Survey, New Jersey Geological Sur- 

 vey, U. S. National Museum. 



Outside Distribution. — Matawan Formation. Marshalltown clay marl, 

 New Jersey. 



"In the Chattahoochee region (Alabama, Georgia) the species makes 

 its first appearance near the base of the Tombigbee sand member of the 

 Eutaw formation. It is common in the upper one-fourth to one-half of 

 the Tombigbee sand in western Georgia, Alabama, and as far north in 

 Mississippi as Monroe or Itawamba County, and in that part of the Tom- 

 bigbee sand which in northern Mississippi represents the time-equivalent 

 of the basal part of the Selma chalk. From the Tombigbee sand it ranges 

 upward to about the middle of the Selma chalk, where the latter is most 

 fully developed in western Alabama and east-central Mississippi; and is 

 present in the corresponding non-chalky marine equivalents of the lower 

 half of the Selma chalk in eastern Alabama and in Georgia, these equiva- 

 lents constituting the lower one-third or one-half of the Ripley formation 

 of this region. In North Carolina the species occurs in the upper marine 

 invertebrate-bearing beds of the Black Creek formation. In Arkansas and 

 northeastern Texas the species occurs abundantly in the Brownstown marl. 

 In Texas the species is abundant in places in the upper part of the Austin 

 chalk and in the lower part of the overlying Taylor marl ; it is also fairly 

 abundant in places in the Anacacho formation which is the time-equivalent 

 in southwestern Texas of part or all of the Taylor marl." — Stephenson, 

 1914. 



Genus GRYPHAEA Lamarck 



Type. — Gryphcea angulata Lamarck. 



" Coq. libre, inequivalve, ayant la valve inferieur concave, terminee par 

 mi crochet saillant en-dessus, courbe en spirale involute, et la valve 

 superieur plus petite, operculaire. Chaniere sans dent. Nul fossette ear- 

 dinale oblongue et arquee. Nul seule impression musculaire dans chaque 

 valve." — Lamarck, 1801. 



Etymology: ypviros, hook-nosed. 



