IQ4 NEW YORK STATE MUSEUM 
measures 27 x 36.8 mm and a smaller cotype in the same collection, 
24.5 X 32.4 mm. The proportions of the carapace hence lie between 
2:3 and 3:4. 
The tergite of the type is but 1.8mm long. A nearly entire specimen 
from Onondaga Valley possesses a carapace 20.6 mm long; its preabdomen 
(perhaps somewhat pushed together) measures 26.5 mm arid the remaining. 
five postabdominal segments about 30 mm. It is widest at the second 
sternite (30.5 mm). The abdomen figured by Whitfield is complete to the 
telson, which is lacking. The specimen is probably slightly reduced in the 
figure, judging from the size of the accompanying carapace, and we have 
not the original at hand. The preabdomenin the figure is 31.5 mm long 
and about 33.8mm wide. The postabdomen is 35.8 mm long and shrinks 
from a width of about 24 mm to ro mm in the last segment. 
Horizon and localities. The type came from a loose boulder near 
Cazenovia, Madison co., N. Y., which by its lithologic character and 
the associated fragments of Spirifer vanuxemi_ shows its deri- 
vation from the Manlius beds. Besides this rather poorly preserved spec- 
imen the State Museum possesses a series of carapaces and a nearly complete 
specimen of this extremely rare form. This entire specimen was found 
loose in Onondaga Valley by Prof. Philip F. Schneider and appears also 
to have come from the Manlius limestone. Of the carapaces, one was col- 
lected by the authors in the town of Litchfield in Manlius limestone, not 
less than too feet above the Eurypterus horizon in the Bertie waterlime; 
another was found loose on Jerusalem hill (probably also from Manlius 
limestone, according to the lithologic aspect of the slab); still another 
was obtained at Cherry Valley falls. A series of carapaces, some of rela- 
tively large size, were obtained in the layers of the Manlius formation at 
the Kolb farm, Crane’s Corners, near Jerusalem hill, Herkimer co., and 
some segments in the waterlime of the Manlius at Manlius village. From 
this it appears that there is a continuous waterlime bed near the top of the 
Manlius formation, extending from Onondaga county to Albany county 
and the species seems to be confined to this layer. Professor Whitfield’s 
