N0.21G9. M0LLU8ES OF CHO CTAWHATCHEE MARL—MANSFIELD. 601 



Color, greenish-gray; size of grains varying from about 0.3 mm. to 

 about 0.9 mm. in greatest diameter; feel, not harsh; effervescing 

 rapidly in hydiochloric acid. 



Under the microscope one sees: 



(1) Small, angular, clear, sand grains, making up about seven- 

 tenths of the mass. The size of the grains varies from about 0.2 mm. 

 to about 0.4 mm. in greatest diameter, the average size of 10 grains 

 taken at random being 0.297 mm. 



(2) Small, mostly rounded, coal-black particles, the size of which 

 varies from about 0.2 mm. to about 0.35 mm. greatest diameter, the 

 average size of 10 particles taken at random being 0.2675 mm. ' 



(3) Irregular, porous, very light gray particles, probably calcium 

 carbonate, the size of which varies from about 0.3 mm. to about 0.9 

 mm., greatest diameter, the average size of 10 particles taken at ran- 

 dom being 0.7965-mm. 



(4) A few specimens of Foraminifera, broken spines of Echino- 

 derms, and shell particles. 



Observations under microscope after treatment of matrix with 

 hydrochloric acid: Numbers 3 and 4 of the above disappeared, while 

 2 separated into fine particles. No. 2 was tested for phosphorus, but 

 no convincmg evidence of its presence was obtained. This material 

 is probably of organic origin. 



The foUowing list gives the famia from near Redbay, and the range 

 of the species identified m other strata. A = upper bed at Alum 

 Bluff; J = beds at Jackson Bluff; = 01igocene; M = Miocene; P = 

 Pliocene : 



