and South Central Pennsylvania. 419 



oozes of calcium carbonate which now form the Valentine 

 were laid down. The absence of fossils in this deposit 

 may be attributed to the nature of the bottom, which at 

 any stage of its growth was unsuitable for fixed or 

 vagrant benthos. 2 The lagoon or off-reef phase appears 

 to thicken slightly to the southeast, the white line on the 

 sketch-map showing the approximate easterly limit of 

 the purest limestone. It has already been pointed out 

 that the extreme southerly sections (Nos. 8, 9, 10) do not 

 contain the Valentine. 



The evidence favors the belief that these sections lie to 

 the east of the original area of the purest limestone, as 

 shown by the dotted extension of the white line on the 

 sketch-map. 



Toward the close of the Valentine phase of deposition, 

 the calcareous sediments became less pure. A few 

 corals, including Columnaria, and the gastropod Maclu- 

 rites logani reappear. This thin zone, which can be dis- 

 tinguished from the highly fossiliferous beds of the 

 Rodman, is only distinctly observed along the Tyrone- 

 Salona line. It signifies the brief return of Carlim con- 

 ditions and necessitates a distinct formational name only 

 in the sections where the Valentine is present. 



Rodman Formation. — The highly fossiliferous lime- 

 stone of this persistent northeast and southwest zone 

 is considerably less pure than the subjacent formations. 

 It contains many Bryozoa and other types of attached 

 benthos, as is evidenced by the plates of crinoids and 

 also the abundant remains of pelmatozoan stems. The 

 formation is best observed in the west but its lowest beds 

 have been observed as far east as Eeedsville. Its fauna 

 and lithology are taken to represent the closing phase of 

 Stones River time. The descriptions of the new species 

 in the prolific and peculiar fauna listed below have 

 already been written and will be published later. The 

 species are: Streptelasma profundum, 8. corniculum, 

 E chinos phcerites aurantium, E. aurantium suecica, E. 

 grandis, Hemiphragma ottaivaense, Dalmanella rogata, 

 Orthis tricenaria, 0. disparilis, Pianodema sub&quata, 

 Leptaena n. sp., L. charlotte, Plectambonites n. sp., Oxo- 

 plecia n. sp., Tetranota obsoleta, Omospira laticincta. 

 Bumastus porrectus, B. transversalis, B. n. sp., Illcenus 



2 My recent examination of the lagoons in the Tortugas group bears out 

 this theory. 



Am. Jour. Sci.— Fourth Series, Vol. XLVI1I, No. 288— December, 1919. 

 29 



