262 [October 
I rather think the latter, as the 9 abdomen is distinctly 8 -jointed. It 
is opaque black, not shining black like the piece behind it. 
In 9 the dorsal and ventral pieces of the 8 th or terminal joint of 
the abdomen are separated by an opening, which, when viewed in pro¬ 
file, is obtrigonate, the dorsal piece being very large and somewhat py¬ 
riform, the large end at the tip, and more than twice as long as the 
ventral, and the ventral being triangular. Viewed from below the 8 th 
ventral is semicircular, and split lengthways to its base. 
The species occurs near Rock Island plentifully, but only on the 
banks of the Mississippi. Sialis americana^ on the other hand, occurs 
more sparingly, and exclusively on the banks of Rock River, the two 
rivers being only 2 or 3 miles apart. 
Note 26, p. 181. Chauliodes lunatus Hag., and serricornis 
Say. The “inferior appendage” spoken of by Dr. Hagen is not, unless 
I mistake, the homologue of the true inferior appendages but of the 
lobe attached to the tip of the penultimate ventral joint in % Sialis. 
(See fig. B, b.) It exists just as he describes it in lunatus, in a spe¬ 
cimen of that species sent to me by Mr. Uhler, the sex of which how¬ 
ever is uncertain because it has lost its antennae, but is manifestly at¬ 
tached to the penultimate ventral. Throughout Neuroptera, Pseudo- 
neuroptera and Orthoptera the true % inferior appendages, whether sol¬ 
dered together as in the Tribes ^schnina and Libellulina, or free and 
prehensile as in the tribe Agrionina, are always, when they exist at all. 
placed behind the last ventral. In my % specimen of 0. rastricornis 
this appendage has apparently been obliterated by stufl&ng the abdo¬ 
men with cotton. If we refer to the closely allied genus Corydalis, we 
shall find that the true inferior % appendages are two in number, wide 
apart, long, forcipate, and freely moveable as in Agrionina, though they 
are anomalous in being attached not to the sternal piece of the venter 
but to what may be called the pleura of the last abdominal joint, 
which is separated from the dorsal piece of that joint by an indistinct 
suture. It might be thought that this entire piece, both dorsum and 
pleura, was the homologue of the superior appendages, and the pieces 
which I consider as the true inferior appendages were mere branches 
of those appendages, but for the fact that the preceding joint % 9 bears 
a distinct spiracle in its lateral membrane and cannot therefore be the 
last abdominal joint. Both in S 9 Chauliodes, so far as can be seen 
