Os 
Clay pole. ] 238 [Sept. 21, 
Considering all these facts I have determined to place the fossil in a new 
genus established to receive it, and named from the elongated head Dol- 
ichocephala. The generic and specific descriptions are necessarily im- 
perfect, being founded on imperfect specimens, but the characters of the 
head are distinct. 
ah og exe 
a.* db, 
a. Kurypterus remipes, 
b. Stylonurus Logani. 
c. Pterygotus Anglicus. 
Limulus rotundatus. 
e. Scale-like sculpture of Dolichocephala, nat. size. 
Ps 
a 
DoLICHOCEPHALA, n. g. 
yenus of Crustaceans allied to Hurypterus. Head-shield only known. 
General outline semi-elliptical (the length being parallel to the major 
axis of the ellipse). Surface slightly convex; margin furrowed. Medial 
line marked with an elevated ridge, beginning near the front, and rising 
into spines or tubercles at different points along its course, sinking again 
to the general level posteriorly. Another obscure and interrupted ridge 
or row of tubercles lies between the median ridge and the margin, and 
another, more or less defined, crosses the median ridge at right angles 
near its hinder extremity. 
Whole surface marked with small, low tubercles, and, beside these, 
with minute delicate scale-like sculpture. 
DOLICHOCHPHALA LACOANA, Nn. Ss. 
General outline as in genus; margin with two narrow furrows and a 
fillet between them, the whole almost a half an inch wide. Median ridge 
