SYNOPSIS OF GENERA. 
li 
Genus STYLONURUS, Page. 1856. 
1856. Stylonurus, Page. Advanced Text-book of Geolog-y. 
1857. Eurypterus, Salter. Edinb. New Pbil. Journ. 
1859. Stylonui'us, Page. Advanced Text-book of Geology, 2d ed. 
1859. Eurypterus ( partim), Salter. Quart. Joui'ii. Geol. Society. 
1859. Eurypteinis, Salter. In Murchison’s Siluria, 3d ed. 
1864. Stylonurus, Woodward. British Assoc. Kept. 
1867. Stylonums. Murchison’s Siluria, 4th ed. 
1881. Equisetides, Dawson. (?) Quart. Journ. Geol. Soc., vol. xxxvii. 
1882. Stylonurus, Martin. Trans. N. Y. Acad, of Sciences. 
1883. Boliclioeephala, Claypole. Proc. Amer. Philos. Soc. 
1883. Stylonurus, Hall. Thirty-sixth Kept. N. Y. State Mus. Nat. Hist. 
Diagnosis. Body in general propor¬ 
tions similar to Eurypterus. Cephalon 
sub-quadrate or sub-pentagonal in 
outline. Eyes large, circular and 
approximate, sometimes surrounded 
by conspicuous orbital ridges. Ocelli 
situated at the posterior extremity of 
a median ridge, passing between the 
eyes. Surface coarsely squamose. 
Cephalic appendages in five (?) pairs, 
the last of which are produced nearly 
to the extremity of the telson. Seg¬ 
ments of the Abdomen as far as known, 
similar to those in general features 
of Eurypterus. Those of the post¬ 
abdomen each bear a pair of lateral, 
detachable processes or epimera. Cau¬ 
dal spine long and slender or sub- 
clavate. 
Restoration of Stylonurus Logani, according to W’oodward. 
