Species of Genus Bunops. 
333 
rations are large, of uniform size, and^their points are directed 
posteriorly. In B. scutifrons the crest is smooth, although 
minute serrations are sometimes seen with a high magnifying 
power. These are not more than four or five, and the points 
are directed anteriorly. They are quite too minute to be shown 
on the scale of my figures. The position of the spines on the 
ventral margin of B. serricaudcita as shown in Daday’s figure, 
seem to indicate that the edges are infolded as in B. scutifrons. 
The head differs in shape. It is smaller, shorter and more concave 
ventrally. The drawing shows a slight curve over the eye, indi¬ 
cating that B. serricaudcita possesses the convexity above the 
eye characteristic of B. scutifrons . The curve is not mentioned 
in the description. The depression between the head and thorax 
is deep. The post-abdomen is very like that of B. scutifrons in 
general outline. There is the same notch dividing it into two 
lobes, with the anus opening on the posterior lobe, the same 
crenelation on the pre-anal portion, and no elevation for the 
abdominal’ setae. The post-abdomen of B. scutifrons , however, 
has more spines than has that of B. serricaudcita ; there is a de¬ 
cided prolongation of the post-abdomen between the anus and 
terminal claws, and the terminal claws are serrate and not smooth 
as in B. serricaudcita. The abdominal setae of B. serricaudcita are 
much longer and bi-articulate, and there is only one ridge before 
them. The antennules are very similar in shape, length and posi¬ 
tion, but do not show the single basal sense-hair found in B. 
scutifrons. The antennae are neither described nor drawn by 
Daday. 
Herrick* described a form which he called Macrot hr ix pauper, 
which probably belongs to this genus, but the description differs 
from B. scutifrons in many particulars. The general shape differs 
greatly. The head projects so as to give an almost triangular 
outline to the animal, while B. scutifrons is nearly round. There 
is a sharp angle where the dorsal joins the ventral part of the 
valve, and the posterior margin is straight instead of concave. 
The post-abdomen is smaller, shows no trace of notch or 
spines and has a wholly different form. Herrick says; “There 
* Geological Report of the State of Minnesota, 1884, pp. 70-71, PI. C, 
Fig. 4. 
