Makylaxd Geological Survey 597 



and upper beds of the Ithaca formation it attains its greatest abundance 

 but continues its existence through the earliest manifestations of the 

 Ohemung fauna. 



In Maryland this species is very rare in the Ithaca and Parkhead, but 

 abundant in the Chemung, ranging from the base of the latter member to 

 the upper conglomerate. 



Occurrence. — Jennings Formation, Chemung Member. National 

 Boad, west of Frostburg; section on Trout Run; Bear Pen Eun; Ellers- 

 lie, Pennsylvania, 1508 ; Little Eun, % mile west of Wills Creek Station, 

 Pennsylvania; National Eoad, on Polish Mountain, 2706, 2929, 3036; 

 Town Creek, 2122, 2228 common, 2450, 2913, 3404, 3453 common, 

 3584 ?, 3593, 3963 small; 2 miles west of Pawpaw, West Virginia, 2190 ?, 

 3540 ; top of Green Eidge ; Fifteenmile Creek, 1 mile above Little Orleans, 

 2286 abundant; east of Baird on B. & 0. E. E., Bellegrove, 300 feet 

 west of Schoolhouse, abundant; Sideling Hill Creek; National Eoad, west 

 of Tonoloway Eidge; Hancock, 2223, 3406 abundant; Millstone, 2345, 

 2390, 2444 abundant, 2470, 2749 abundant, 2761, 2796; Berkeley 

 Springs, West Virginia, 2158 abundant. Parkhead Member. Two miles 

 north of mouth of Town Creek, 1723; 2 miles west of Pawpaw, West 

 Virginia; Millstone, 1672, 1694, 1811 abundant, 1916; Berkeley Springs, 

 West Virginia, 1554 to 1566. Woodmont Member, Ithaca Fauna. 

 Hancock, 1149 to 1274; Yellow Springs, West Virginia, 734. 



Collection. — Maryland Geological Survey. 



Spirifer marcyi var. superstes n. var. 



Plate LVII, Figs. 6-11 



Description. — Spirifer marcyi is a species which occurs with some 

 frequency in the soft calcareous shales of the Hamilton group at certain 

 localities in western New York and Avas described and fully illustrated 

 by Prof. Hall in vol. iv, Paleontology of New York, p. 226, pi. xxxvii, 

 figs. 10-80. The species is characteriized by its broad, many-ribbed lateral 

 slopes, each full-grown shell bearing about 30 flattened plications on each 

 of these slopes ; low, smooth fold and sinus, and having the surface of pli- 



