RANGE AND DISTRIBUTION OF RETICULARIA LAEVIS 189 



flourished alongside and to the westward of the Ithaca fauna. At the 

 best-known locahty of its occurrence R. laevis is found abundantly 

 through 3 feet of strata, above and below which it is unknown for a 

 considerable interval. At this locality, which is at the foot of Ithaca 

 Falls, at Ithaca, N. Y., the associated fauna, as determined by the 

 writer,^ is as follows: 



Lingula ligea ? r. Modiomorpha subalata 



Crania sp. r. Grammysia subarcuata r. 



Chonetes lepida a. Glyptocardia speciosa r. 



■ Chonetes scitula r. Nucula diffidens r. 



Leiorhynchus mesacostalis Mytilarca chemungensis ? r. 



Cyrtina hamiltonensis r. Leda diversa 



Spirifer laevis a. Pleurotomaria capillaria r. 



Lunidicardium fragile a. Orthoceras pecator r. 



Paleoneilo filosa a. Tomoceras discoideum c. 



Ariculopecten rugaestriatus ? Taxacrinus ithacensis 

 Aviculopecten lautus var. ithacensis r. 



This zone of Sp. laevis is about 250 feet above the Genesee shale 

 and near the top of the Sherburne sandstone. It lies below the 

 typical Ithaca fauna at a horizon where more or less intermingling of 

 the Naples and Ithaca faunas occurred. The Ithaca element of the 

 fauna is seen in the brachiopod species, while the western fauna is 

 represented by such forms as Lunulicardium jr agile and Glyptocardia 

 speciosa. 



This horizon, from which the species was described by James 

 Hall in 1843,^ remained the only one known for it till forty years 

 later, when Williams found it near the top of the Ithaca fauna, ^ at a 

 single locality in the Fall Creek section about 400 feet higher. 



While studying the Ithaca fauna in 1896 the writer found a third 

 zone of Reticularia laevis at Ithaca in the McKinneys Station section, 

 which is 120 feet below the zone at the foot of Ithaca Falls. -^ 



The discovery of this third zone extended the known vertical 

 range to about 520 feet. The upper zone of the species at or near 

 the top of the Ithaca group had not been relocated since its discovery 



^Bulletins oj American Paleontology, No. 6 (1896), p. 17. 



2 Geology of New York, Report of Fourth District (1843), P- 245, fig. 



3 Bulletin No. 3, U. S. Geological Survey, 1884, p. 20. 

 '^Bulletins of American Paleontology, No. 6 (1896), p. 28. 



