ORTMANN: THE CRAWFISHES OF THE STATE OF PENNSYLVANIA 395 
on the posterior lateral corners with one or two spines. Posterior section semi-ellip- 
tical, distinctly wider than long, about as long as the anterior section. 
Epistoma with posterior part comparatively long, hardly one and one-half times 
as broad as long; transverse groove indistinct and close to posterior margin; an- 
terior median depression also indistinct, and thus the posterior part of the epistoma 
appears rather flat and smooth. Anterior section constricted at base, semi-circular 
or semi-elliptical or subquadrate, rarely with a median anterior point, often more or 
less truncate anteriorly, or even slightly emarginate. Transverse diameter never 
greater than longitudinal, as great as the latter or shorter. 
Antennula with a small tubercle on the lower margin of the basal joint. 
Antennal peduncle without distinct spines or tubercles on the two proximal, 
joints. 
Antennal scale short and small, slightly longer than the rostrum, and not reach- 
ing beyond the distal end of the fourth joint of the antennal peduncle. Spine of 
outer margin strong. Laminar part only slightly wider than the spine. 
Flagellum short, not reaching beyond the third abdominal segment in the male, 
and not beyond the second segment in the female, but often hardly longer than the 
carapace. 
First pereiopods (Pl. XL, Fig. 4) short, not very robust, not undergoing much 
change with age, and not differing much according to sex. Hand ovate, broad and 
depressed. Surface punctate. Inner margin of palm convex, with a single row of 
distinct tubercles, larger proximally; occasionally there is a second, incomplete row 
inside of and parallel to this. Outer margin smooth and rounded proximally for 
a short distance, but soon becoming angular and forming a distinct ridge along the 
edge in the region of the base of the immovable finger. This ridge has a regular 
row of deep punctures, giving the distinct appearance of serrations along the outer 
margin of the hand. Fingers as long as, or slightly longer than the palm, slightly 
gaping at the base in both young and old individuals, straight. Outer margin of 
moyable finger with punctures, but very rarely with tubercles. Cutting edges with 
a few irregular tubercles in the proximal half. Upper surface of each finger with 
a low rib, bordered by rows of punctures. 
Carpopodite slightly longer than wide, about as long as the palm, with a deep 
longitudinal sulcus above. There is always a strong, more or less pointed, spine on 
the inner margin, directed obliquely forward, and a strong, often spiniform, conical 
tubercle in the middle of the anterior margin of the under side, (rarely obsolete). 
The tubercle at the lower articulation with the hand is low and indistinct. Rarely 
there are accessory tubercles, which, however, are never spiniform. The most fre- 
