10 
PALEONTOLOGY OF NEW YORK. 
of the lower surface impressions of the projecting edges of these tuhules 
are also visible. Between these openings may be seen minute pittings which 
are the openings of smaller tubules. 
Dimensions. An average example affords the following measurements: 
Body. Cephaloii. Thorax. Pygidinm. 
Length_ 156 mm. 40 mm. 73 mm. 43 mm. 
Width_ 75 mm. 75 mm. 73 mm. 48 mm. 
The largest entire individual observed has a length of 220 mm. and a width 
of 100 mm.; the smallest a length of 10 mm. and a width of 6 mm. 
Observations. Homalonotus Dekayi, the latest and most prolific representative 
of the genus in America, differs from the Homalonoti of the earlier Devonian 
and the Silurian, both in this country and Europe, in tlie obsolescence of 
the annulations of the pygidium at maturity. It is an abundant fossil in the 
sandy shales of the Hamilton group of the central counties of the State where 
it is usually preserved in the form of casts. West of Cayuga county it is of 
much rarer occurrence and appears to be mostly confined to the shales above the 
Encrinal limestone. In Genesee and Erie counties it is very seldom met with, 
and in the eastern outcrops of this formation in Schoharie and Albany counties 
it is not abundant. 
Distribution. Hamilton group. In the Marcellus shales on Flint Creek, 
Ontario county; in the Hamilton shales at Bear’s Gulf, near Summit, Schoharie 
county; Cazenovia, Leonard ville and Hamilton, Madison county; East Worcester 
and elsewhere, Otsego county; Pompey Centre, Pratt’s Falls and Delphi, Onon¬ 
daga county; Bellona, Yates county; Hopewell and West Bloomfield, Ontario 
county; Tichenor’s and Menteth’s^ Points, Canandaigua Lake; Darien, Genesee 
county; Hamburgh and Eighteen-mile Creek, Erie county. 
=*=This name as used in the pi-evious publications on the Paleontology of New York, and as spelled by the 
original owner of the property on Canandaigua Lake, was Monteitli. It is now undei'stood that its present 
owner has changed the spelling of the name to Mentcth. 
