Maryland Geological Survey 425 



to be characteristic of the Chemung in New York. Clarke/ however, 

 cites it from the Ithaca of 'New York, while Williams and Kindle ' 

 identify it in the Ithaca fauna at Catawissa, Pennsylvania. Its occur- 

 rence below the range of the Chemung fauna in Maryland is well estab- 

 lished. Liorliynchus cjlohuUfonne is assigned by Williams'' to a higher 

 horizon in New Y^ork, but is quoted from the Ithaca fauna of east-central 

 New York, by Clarke.* The fauna includes thirty species, of which 

 three are new. Of the previously described forms, twenty-two or 73 per 

 cent, occur in the Ithaca fauna of New York or Pennsylvania. Four 

 not found in the Ithaca fauna of those states occur in the Hamilton of 

 New York, while but one species, Grammysia communis, has not been 

 hitherto reported in horizons below the Chemung. Thus all but one of 

 the previously described species are found in the Hamilton or Ithaca 

 of New York or Pennsylvania. These facts fully justify the correlation 

 of this fauna with the Ithaca fauna of New York. 



It has already been shown that the Ithaca fauna of Maryland possesses 

 a considerable vertical range in the eastern sections but becomes more 

 restricted and finally vanishes in the west, where it is replaced by the 

 Naples fauna. In this respect it also resembles the Ithaca fauna of 

 New York. The beds containing this fauna consist more largely of shales 

 than do the underlying strata in either Maryland or in New York. 



Cladochonus-Reticularia Icevis Zone. — The lower zone of the Ithaca 

 of Maryland has been designated the Cladoclwnus-Reiicularia Icevis zone 

 from its most characteristic species, Cladochonus humilis and Reticularia 

 IcBvis. All the species of the zone, save two new species, occur in the 

 Ithaca of New York and nearly all in central New York. A species of 

 Cladochonus, which is not improbably the same as one found in Maryland, 

 is common in the lower portion of the Ithaca beds at Ithaca, New York. 

 Reticularia Icevis occurs at two horizons at Ithaca, one near the base and 



' BulL N. Y. State Museum, No. 82, p. 62, 1905. 

 = BulL U. S. GeoL Survey, No. 244, p. 77, 190.5. 

 = Folio No. 169, U. S. Geol. Survey, p. 6, 1909. 



■■ Ithaca fauna of Central New York, Bull. N. Y. State Museum, No. 82, p. 64, 

 1905. 



