568 Systematic Paleontology 



This subspecies is particularly characteristic of the Canal and the 

 yicinity of Bohemia Mills, where it occurs very much more abundantly 

 than the normal type of the species. 



Occurrence. — Matawan Formation. Two miles west of Delaware 

 City, on John Higgins farm, Tost 236, Camp Fox, Post 208, Post 192, 

 Camp U & I, Post 136 and Post 133, Chesapeake and Delaware Canal, 

 Delaware. Monmouth Formation. Head of Bohemia Creek, Bohemia 

 Mills, and ? mouth of Turner's Creek, Kent County, Maryland. 



Collections. — Maryland Geological Survey, U. S. National Museum, 

 Philadelphia Academy of Natural Sciences. 



Outside Distribution. — Monmouth Formal ion. ? Navesink marl, New 

 Jersey. 



" This variety makes its first apearancc approximately coincident with 

 the initial appearance of the typical, strongly costate forms; that is, at 

 the base of the zone of Exogyra costata; it has not been found in asso- 

 ciation with typical specimens of Exogyra ponderosa Eoemer. In the 

 lowermost beds of its stratigraphic range, especially in Mississippi, it 

 appears to exceed in numbers the typical costate forms. In the successively 

 higher beds it appears to decrease in numbers, and it is absent, so far as 

 known, from the upper 80 or 100 feet of strata in Mississippi and western 

 Alabama, and probably from a somewhat greater thickness in the Chat- 

 tahoochee region. In the Carolinas the form occurs in the Peedee sand, 

 the known localities being near the base of that terrane ; that is, near the 

 base of the zone of Exogyra costata. In Arkansas the variety occurs 

 abundantly in the Malbrook marl. In Texas the variety has been obtained 

 from three localities, all of which are probably near the base of the 

 Navarro formation. The first locality is one-half mile north of Cooper, 

 Delta County, and the second and third are 4 and 4| miles, respectively, 

 east of Crandall, Kaufman County. Three typical specimens of this 

 variety, brought from Mexico in 1906 by Dr. T. W. Stanton, were given 

 to him at San Luis Potosi and were said to have been collected from a 

 locality near Ciudad del Maiz, State of San Luis Potosi." — Stephenson, 

 1914. 



