TRILOBITES. 741 
Encrinurus cristatus.] 
ENCRINURUS ORISTATUS, 2%. Sp. 
There is a portion of a small cranidium from the horizon of the Hudson River 
eroup at Spring Valley, Minnesota, which presents a series of striking characters, 
and in the absence of negative evidence may provisionally be regarded as a new 
Fig. 58.—Cranidium of Ancrinurus cristatus. x 3. 
species. The glabella is obconical, its narrow, blunt extremity being directed posteri- 
orly and conspicuously elevated. It extends almost if not quite to the occipital margin, 
over-hanging the posterior edge. The dorsal furrows are very deep and constrict 
the glabella laterally. The glabellar furrows are represented by three deep puncte 
at the bottom of the dorsal furrows, and these afford evidence of four pairs of lateral 
lobes; the first very small on the margin and limited by a faint groove extending 
upward over the surface of the glabella; the second and third also narrow and linear, 
are immediately merged into the median lobe, while the fourth pair is better 
developed than the rest, extends entirely across the dorsal furrows, connecting the 
eye-node with the anterior extremity of the glabella. 
The glabella bears upon its upper surface a few (25) coarse, distant tubercles, 
which on the posterior portion are elongated, directed obliquely backward and 
upward, and take on the form of blunt spinules. From the middle point on the 
anterior margin of the glabella diverges a pair of shallow grooves, which skirt the 
ante-lateral margins and become obsolete on the lateral slopes. These grooves, 
which apparently indicate the course of the facial sutures-on their anterior limbs, 
cut off a narrow ridge on each side of the anterior margin and each of these ridges 
bears a single row of four strong spiniform tubercles. The lateral and posterior 
concave slopes of the glabella are smooth. The length of this glabella is 5 mm. 
A portion of the left eye-node is retained and appears to have been moderately 
elevated though not to the hight of the glabella; the eyes were approximate and 
posterior. Among the Russian species of Encrinurus described by Schmidt, we find 
a very close ally to H. cristatus in his . seebachi, from the Wesenberg horizon (op. 
cit., pl. xrv, figs. 16—26). In the latter the glabella is less convex and more abund- 
antly tubercled; but the posterior tubercles are equally spiniform, and the anterior 
row is clearly delimited though not divided in the center. 
