342 NEW YORK STATE MUSEUM 
Besides the carapaces, on which the species is based, a half complete 
specimen [pl. 85, fig. 13] has been obtained. This exhibits a form of the 
preabdomen corresponding to that of H. socialis, the genotype, if 
the slight axial contraction of the specimen is taken into account. The 
swimming leg of the right side can be distinguished in its outline. It is 
relatively longer than that of H. socialis. 
Besides the carapaces two detached chelicerae resemble in their strong 
development and long pointed pincers more those of Hughmilleria than 
of any other genus [pl. 85, fig. 17, 18] and also detached body rings 
[pl. 85, fig. 19] exhibit a type of ornamentation, consisting of transverse lines 
near the anterior margin, known to us only in H. shawangunk, 
the Otisville representative of the genus. 
Hughmilleria shawangunk Clarke 
Plates 64-66; 69, figure 1 
Hughmilleria shawangunk Clarke. N. Y. State Mus. Bul. 107. 1907. 
p. 308, pl. 4, fig. 1-4; pl. 5, fig. 1-9 
Description. Hughmilleria shawangunk attains but half 
the size of the genotype, or about 8 cm and is therefore one of the 
diminutive species of eurypterids. In outline of body and form of head 
it closely resembles H. socialis; itis slender and terete, but slightly 
wider in the middle of the preabdomen than at the base of the carapace, 
and lacks any marked contraction from preabdomen to postabdomen. 
With the anteriorly rounded, subtriangular carapace and marginal eyes, 
the dorsal aspect of the animal is singularly fishlike and suggestive of 
great agility. 
Cephalothorax. The carapace is semielliptic in the mature form, 
wider than long by one sixth to one fifth, comprises one fifth the length 
of the body or more; as preserved it is subject to great variations in 
outline, mostly due to variously directed compression and wrinkling after 
entombment and to an originally thin test. The lateral margins of the 
carapace are slightly convex, the frontal part acutely rounded. The 
