267 
[Foerste. 
pleurae are all distinct. The following measurements will show the 
range of variation : 
LENGTH IN MM. 
BREADTH IN MM. 
WIDTH OF ME- 
DIAN LOBE. 
NO. OF SEGMENTS 
ON MESIAL 
LOBE. 
NO. OF PLEURJE. 
17 
27.6 
10 
8-9 
5 
14.5 
24 
8.2 
8-10 
5 
11.5 
18.7 
6.7 
9-10 
5 
10.5 
16.7 
6.5 
7-9 
5 
S.l 
13.4 
5 
5-8 
5 
7.5 
13 
4.3 
7-10 
5 
Calymene Clintoni , Vanuxem, is readily distinguished from the 
above variety by the decided contraction of the glabella antero-pos- 
teriorly, the narrow anterior border of the head, and the compara- 
tively smooth lateral lobes of the pygidium ; sometimes faint indi- 
cations of segments may be noticed upon these. We have seen no 
authentic specimens from localities outside of New York. 
Calymene rostrata, Yogdes. 
Calymene rostrata , Yogdes, was briefly described in the Am. 
Journ. Sci. Arts. 1879, for December. It was found originally in 
the Clinton Group at Catoosa Station, Georgia. Later it has been 
found elsewhere in Georgia and also in the arenaceous Clinton 
beds of New York. 
Calymene nasuta , Ulrich, was described in the Cincinnati Journ. 
Nat. Hist., 1879, for October, which however was not received at 
the Harvard Libraries until Feb. 19, 1880, about which time it prob- 
ably was published. This form was found at Osgood, Ripley 
county, Indiana, in the lower beds of the Niagara group. Not 
having seen the Indiana specimens we find it impossible to pro- 
nounce upon the identity or similarity of these species. The an- 
gle at which the head of the Indiana forms is figured does not 
assist us. It may be remarked, however, that these forms are 
very closely related, that the New York specimens are often quite 
large and that the end of the snout is not so pointed as a rule, as the 
first published figure would indicate. 
Illaenus ambiguus, Foerste. 
Two glabellse presenting all the interior and exterior aspects of 
