RAYMOND: NEW AND OLD SILURIAN TRILOBITES. 25 
Barrande, and, on the other hand, though the pygidia in the Day 
collection are much like that of A. portlocki, their cephalons are very 
unlike those assigned to A. portlocki by Barrande. 
Formation and locality: —'The specimens figured are from the 
-Niagaran at Wauwatosa, Wisc. 
ENCRINURIDAE Angelin. 
ENCRINURUS REFLEXUS, Sp. nov. 
Plate. 3, fig. 7,8. 
The Day collection contains several pygidia of an Encrinurus which 
is larger and differs in various ways from any species of this genus 
heretofore described from Silurian strata of this country. 
Cephalon and thorax unknown. 
Pygidium large for the genus, triangular, pleura bent abruptly 
downward, the posterior end somewhat turned up. Axial lobe very 
long, tapering backward to a point. It is marked by about thirty 
rings which are prominent and sharp toward the front, but very faint 
at the posterior end. With the exception of two at the anterior end 
the rings do not cross the axial lobe, but leave a narrow smooth space 
along the median line. Along this smooth lane are disposed eight 
pustules, approximately evenly spaced. On the pleural lobes are 
eight pairs of broad flat ribs which curve backward, making a rather 
abrupt turn near their outer ends. They.do not reach quite to the 
margin, and end in blunt free spines which project from the sides a 
little above the margin. At the posterior end the last two ribs from 
each side converge alongside the axial lobe, and, with a small median 
spine, project beyond the end of the axial lobe. The ribs have small 
pustules scattered somewhat irregularly over them, and not aligned 
in longitudinal rows. Nearly every rib has a. pustule at its inner end 
and one near the middle. Some of the ribs have only these two, but 
the longer ones near the front have another. 
Measurements: — 'The more complete of the cotypes is 28 mm. long, 
26 mm. broad at the front. The axial lobe is 9.mm. wide at the front 
and 26 mm. long. 
Comparison with other species: — Nine species of Encrinurus have 
previously been described from the Silurian of America, but most of 
them are of much smaller size than the present species and only two 
" 
