. Annual report. New York State Museum; Science; Science. l66 NEW YORK STATE MUSEUM no means of knowing the other parts of the animals thus designated by Hall. In the Grande Greve rocks these large, coarsely tubercled cephala have the thoracic segments knotted at the dorsal furrows as in large specimens of Ph. 1 o g a n i. In smaller specimens these thoracic characters are obscured except in the cast, but the cephalic shields of the latter do not show the spinules of the Perce species and of typical P. 1 o g a n i. The variations of expression in the representatives of the genus Phacops in the
. Annual report. New York State Museum; Science; Science. l66 NEW YORK STATE MUSEUM no means of knowing the other parts of the animals thus designated by Hall. In the Grande Greve rocks these large, coarsely tubercled cephala have the thoracic segments knotted at the dorsal furrows as in large specimens of Ph. 1 o g a n i. In smaller specimens these thoracic characters are obscured except in the cast, but the cephalic shields of the latter do not show the spinules of the Perce species and of typical P. 1 o g a n i. The variations of expression in the representatives of the genus Phacops in the New York Devonic are slender and identifications are always obscure. Fixing upon the following characters as critical, viz, the .cristation of the genal angles, the knotting of the thoracic segments and the grooving of the pleural ribs on the pygidium, we may tabulate the species thus: Cheeks Thorax Pygidial ribs P. logani (Helderbergian) faintly spined knotted duplicate P. cristatus (Schoharie grit) strongly spined smooth duplicate P. c ristat a var. pip a (Onondaga) faintly spined smooth duplicate P. bombifrons (Onondaga) smooth smooth duplicate P. r a n a (Hamilton-Ithaca) smooth smooth simple In this schedule the Grande Greve species takes a place close to P. logani; the Perce form, which is always small, is a near ap- proach to the typical expression of the species. Lower Devonic. Everywhere along the Florillon from Ship- head to Little Gaspe, and in the blocks of limestone from the sec- ond range found in the stream bed at Peninsula. Also at the Ruisseau du Grande Cavee associated with Dalmanites grif- fon i, and in Perce rock, P. Q. Phacops (Phacopidella) nylanderi nov. This is an addition to the peculiar group of early Devonic species of which we recognize the following other members: P. b r a s i 1 - i e n s i s (Maecuru), P. a n c e p s (Decewville), P. correlator,. Phacops (Phacopidella) nylanderi New York Oriskany and Gaspe sandstone. We have noted in what respects
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