52 The Upper Cretaceous Deposits of Maryland 



Maryland in Earitan time, although possibly entering the region in the 

 southern part of the district during the Magothy epoch as has been shown 

 to be true in New Jersey in the vicinity of Cliff wood. The organic remains 

 therefore of the Raritan and Magothy are chiefly of vegetable origin and 

 represent a still further advance in development over the floras of the 

 Patapsco formation of the Lower Cretaceous. With the opening of 

 Matawan time the marine waters transgressed upon the land, and we 

 find during the Matawan and Monmouth epochs a deposition of marine 

 sediments containing an extensive fauna of Upper Cretaceous age. 



The molluscan fauna of the Upper Cretaceous of Maryland includes 

 223 species, 129 pelecypods, 84 gastropods, 1 scaphopod and 9 cephalopods. 

 These are segregated into 53 genera and 32 families of pelecypods, 38 

 genera and 26 families of gastropods, 1 genus and 1 family of scaphopods 

 and 8 genera and 8 families of cephalopods. 



All of the Upper Cretaceous horizons except the Raritan have yielded 

 invertebrate fossils. The Magothy fauna, however, is very meager, con- 

 sisting of 5 or possibly 6 species of bivalves and 1 univalve. Three out 

 of the 6 or 7 species are restricted in their known distribution to the 

 Magothy, 1 has not been recognized except from the Magothy and Mata- 

 wan, 1 or possibly 2 range through the Magothy, Matawan and Mon- 

 mouth and 1, the ubiquitous Pecten quin que co status, occurs at all hori- 

 zons from the Magothy to the Rancocas. 



The Matawan fauna is quite prolific, 75 or possibly as many as 83 

 species in all, including 48 to 53 pelecypods, 21 or 22 gastropods and 6 

 cephalopods. Approximately 57 per cent of these species are restricted 

 to the Matawan. The restricted pelecypods are rather less than 50 per 

 cent of the total, but 16 out of 22 of the gastropods and all of the cephalo- 

 pods are peculiar. The strongest affinities of the fauna are with the 

 Monmouth, 29 to 36 species, almost 43 per cent, being common to the two 

 formations, while only 3 or possibly 4 species range downward and only 3, 

 all of them bivalves, persist into the Rancocas. However, it is probable 

 that if the Magothy and Rancosas formations were as well represented 

 as the Matawan and Monmouth the number of common species would be 

 greatly increased. 



