18 
PALEONTOLOGY OF NEW YORK. 
Phacops bombifrons with Phacops cristata, with the more abundant material 
now accessible, appears to be indisputable. There remains, however, a form of 
Phacops, abundant in nearly all the outcrops of the Corniferous limestone in 
the State, which it was not intended to include under the original diagnosis of 
Phacops bombifrons, and which has hitherto remained unnoticed in any published 
description, or has been tacitly referred to the species Phacops rana. A careful 
examination has proven that Phacops rana occurs with extreme rarity, if ever, 
in this formation, and that the specific affinities of these abundant individuals 
are much too close to Phacops cristata to justify their recognition as an indepen¬ 
dent species. They may be tentatively regarded as a prolific variety of Phacops 
cristata, under the following designation. 
Phacops cristata, var. pipa, n. var. 
PLATE VIII A, FIGS. 5-18. 
The essential points of difference between this form and the normal Phacops 
cristata, are the following; (a) greatly inferior size, (b) absence of the axial row 
of spines, (c) smaller spines at the genal angles, (d) fewer annulations upon the 
pygidium, (e) smaller number of corneal lenses, varying, as ascertained from 
measurements of a large number of specimens, from twenty-three to forty-five 
for each eye. They agree with Phacops cristata in (a) general proportions, 
(b) gibbosity of the glabella, (c) presence of the genal spines, which though 
sometimes faint may always be detected, (d) crenulated sub-marginal sulcus, 
(e) obtuse termination of the axis of the pygidium, (f) dichotomous annula¬ 
tions on the pygidium, (g) similar surface ornamentation. A single pygidium 
of this variety from the decomposed Corniferous chert of Ontario county, is of 
exceptional interest as showing on a cast of the inferior surface seven pairs 
of muscular impressions just within the margins of the axis. 
The dimensions of an average entire individual are; length 26 mm.; width 
16 mm. The smallest observed has a length of 12 mm., and a width of 7 mm. 
Distribution. Phacops cristata. Oriskany sandstone; Cayuga, Province of Ontario, 
associated with Dalmanites anchiops, Green, Spirifera arrecta, Alal\, Streptorhynchus 
(Orthis) hipparionyx, Vanux., Rmssclcxria oroides, Hall. Upper Helderberg group; in 
the Schoharie grit, near Clarksville, Albany county; Schoharie, Schoharie county. 
