M vkyland Geological Survey 69 



The Mortoniceras fauna is a relatively deep-water fauna and notable 

 for the absence of the Ostreids. In this respect it stands in marked con- 

 trast to the fauna which is most typically developed to the eastward in 

 the vicinity of Camp Fox, opposite Post 236, on the Chesapeake and 

 Delaware Canal. By far the most conspicuous element in the latter, from 

 the point of view of both numbers and size, is the Ostreids. At certain 

 localities, notably at Camp Fox, the beach is paved and the side of the 

 Canal heavily studded with Oryphcea vesiciilwis. Exogyra cancellata, 

 which occurs near the top of the E. ponderosa zone and the base of the 

 E. costata zone, is ubiquitous throughout the restricted area in question 

 but less prolific than G. vesicularis. Ostrca falcata is also a characteristic 

 form, though less conspicuous by reason of its smaller size. A number of 

 species of the smaller bivalves and univalves occur but none of them is 

 abundant, while the cephalopods are very rare. The general aspect of the 

 fauna is very similar to that of the Marshalltown of New Jersey which, 

 like the fauna west of St. Georges, is best characterized by the abundance 

 of the ponderous Ostreids. 



The Matawan fauna from the Magothy Eiver in northern Anne 

 Arundel County is very meager, but is more homogeneous in general 

 character and is less readily separable into faunules than is that along the 

 canal. The fauna includes a few characteristic Merchantville types, such 

 as Schapldtes hippocrepis, but it also includes a number of the forms 

 restricted in New Jersey to the Upper Matawan and a few southern 

 species which characterize the Exogyra ponderosa zone, such as Cucul- 

 Icea carolinensis, which has not been recorded from the Cretaceous farther 

 north. The fauna, on the whole, is more cosmopolitan than any occurring 

 to the northward and was probably laid down in a more open sea which 

 was more accessible from the south. 



The Matawan formation is the equivalent of the upper part of the 

 Black Creek formation of North Carolina and is also represented in the 

 Eutaw formation, and probably the lower part of the Kipley formation 

 and its equivalent the Selma chalk of the eastern Gulf region. The forms 

 point to the Turonian age of the beds. 



