TRILOBITES. 739 
Enerinurus vannulus.] 
Family ENCRINURID &. 
Genus ENCRINURUS, Emmrich, 1844. 
ENCRINURUS VANNULUS, 2. Sp. 
Animal small, ovate in outline, tapering posteriorly from the base of the 
cephalon; protuberant anteriorly. Cephalon with entire, broadly subcircular anterior 
margins, genal angles obtusely rounded, surface elevated, flattened above. Glabella 
protuberant, its convex frontal lobe extending considerably beyond the anterior 
margin of the shield; obovate; greatest width across the anterior portion of the 
frontal lobe and equal to the axial length. Anterior margin subcircular to the dorsal 
furrows which are deep, convergent and slightly incurved. Lateral furrows obscure, 
but still more distinctly developed than is usually the case in species of this genus. 
The first pair lies a short distance from the anterior extremities of the dorsal 
furrows, is short and directed somewhat anteriorly; the second and third furrows 
are but slightly longer, somewhat more transverse. None of these pass far inward 
and their inner extremities are separated by a regularly convex median portion of 
the glabella. They are equidistant and the lobes are, therefore, of about the same 
size. One-half the length of the glabella is taken by the frontal lobe and the width 
of the glabella at its base is one-half its width at the base of the frontal lobe. 
Occipital groove narrow, occipital ring broader than the lateral lobes and extending 
considerably beyond the base of the glabella, forming a proportionally broad axis. 
Hye-nodes very convex, the eyes themselves being small, elevated and situated at 
about the middle of the cheeks. Outwardly, beneath the eyes, the surface is 
depressed convex. The facial sutures terminate posteriorly, directly at the genal 
angles. The occipital groove is clearly defined over the cheeks and is continuous 
with a lateral marginal groove. Surface coarsely and evenly tubercled over the 
glabella and the cheeks, within the marginal furrow. 
Fig. 56.—Encrinurus vannulus. x 2. 
Thorax broad, flattened above, abruptly depressed at the sides. Segments 
normally eleven, but ten are preserved in the single specimen in which this part is 
retained. Axis broad, gently convex; it widens posteriorly from the first to the fifth 
segment, thence gradually tapering. The pleurz, at about the middle of their width, 
