THE EURYPTERIDA OF NEW YORK 341 
smaller. However, it is considered that the differences shown by the 
incomplete material of the collection are not, of themselves, sufficient 
- to warrant the founding of a distinct species. 
We have not obtained any further material that would qualify the 
inferences here set forth. 
Horizon and locality. Pittsford shale at Pittsford, N. Y. 
Hughmiulleria magna nov. 
Plate 85, figs. 11-19 
Description. Carapace semielliptic, length and basal width subequal, 
lateral margins gently curved, subparallel, frontal margin bluntly angular 
so as to form a triangular front to the carapace. Posterior margin straight 
transverse or very slightly concave; genal angles roundish rectangular. 
Lateral eyes large (a little more than one third the length of the cara- 
pace), submarginal, oval in outline. Ocelli subcentral, their tumescence 
between the posterior ends of the lateral eyes. 
No ornamentation has been observed on the carapace. 
Horizon and localities. Frankfort shales. The great majority of the 
specimens are from the Dettbarn quarry at Schenectady, where in one layer 
the species is quite common. A few carapaces have also been found at 
Duanesburg and Rotterdam Junction, Schoharie county. 
Remarks. The form of the carapace is subject to much variation in 
outline, obviously through the stretching and wrinkling of the thin, drifted 
integuments in various directions. The carapace selected as the type 
[pl.85, fig. 11] 1s smooth and but little distorted. When the test is com- 
pletely flattened out, the lateral eyes are seen to be separated from the margin 
of the carapace by a narrow strip, half as wide as the eye, contracted for- 
ward and broadening backward as in the genotype. 
The type measures 17.5 mm in length and 20 mm in width. The 
eyes are 7 mm long. Several carapaces indicate that this species reached 
much larger dimensions than its supposed later allies. The original of 
plate 85, figure 16 is 58 mm wide and 42 mm long. Its lateral margins are 
completely flattened out and the specimen somewhat compressed in the 
axial direction. 
