DEVONIAN, SECTION OF TRHAGCA, Ni. Y. 107 
contain the smaller form of the genus called Orthis (Dalmanella) 
leonensis. 
In the Chemung rocks of western New York the genus is almost 
as conspicuous as Spirifer disjunctus or Orthothetes chemungensis. 
Taking in all the evidence the conclusion is drawn that Dalman- 
ella is a characteristic genus throughout the whole Chemung in the 
western New York section; is more rarely present in the faunules 
of Genesee Valley; is conspicuous in the early and middle zones of 
the Chemung in the sections of Watkins Glen quadrangle; is rare 
in the Catatonk quadrangle, and is rarely ever seen further eastward. 
The species Orthis (Dalmanella) tioga Hall,* was described from 
specimens derived near Factoryville in Tioga County, along Cayuta 
Creek, at Chemung Narrows, near Elmira, at Horseheads, and at 
Bucks quarry. It was also obtained from Allegany County at 
Phillipsburg, and near Leon and other places in Cattaraugus 
County, N. Y. 
The species Orthis (Dalmanella) leonensis Hall,? is a smaller species 
and in the original description it is cited only from the Chemung 
group near Leon, Conewango and Randolph in Cattaraugus County, 
N. Y. 
The Dalmanella leonensis zone.—Investigations into the range of 
the species of the genus in the Watkins Glen thirty-minute quadrangle 
show that the small form Dalmanella leonensis is confined to the lower 
one hundred feet (or a little over) of the Cayuta member of the Che- 
mung formation. As it is often quite abundant in that zone the name 
Dalmanella leonensis zone is appropriately applied to it. 
Common associated species of the faunule are: Leptostrophia 
interstrialis; Productella spinulicosta; Spirifer disjunctus; Reticu- 
laria laevis; Palaeoneilo brevis; Pterinea chemungensis. 
Above the zone of Dalmanella leonensis the species D. tioga appears 
and in the sections along the meridian of Ithaca ranges upward through 
the Cayuta and Wellsburg members of the Chemung formation. 
Spirifer disjunctus (Sowerby) may be regarded as a diagnostic 
species of the Chemung formation throughout New York state and its 
extension into Pennsylvania, Maryland, and Virginia. There are cases 
t Paleontology of New York, Vol. IV (1867), p. 59. 
2 Op. cit., Vol. IV (1867), p. 62. 
