ORTMANN: THE CRAWFISHES OF THE STATE OF PENNSYLVANIA 379 
it proximally. Lower surface with a blunt conical tubercle in the middle of the 
anterior margin (occasionally spiniform). The tubercle at the articulation with the 
hand is generally obsolete. There are sometimes additional tubercles; the one 
which most frequently occurs is a small spine or tubercle between the large one on 
the inner margin and that on the anterior margin of the lower side. | 
Meropodite smooth, with 1-3 tubercles near the distal end of the upper margin, 
one of which is often spiniform in young specimens; in old specimens they are 
generally very indistinct or wanting. Lower side with two rows of spiniform 
tubercles. The outer rows consist of 1-6 (very rarely only one tubercle). Six were 
found in only one instance, that of a regenerated cheliped. Generally there are 
two or three. The inner row has 6-11 spiniform tubercles, of which the distal is 
the largest. A small tubercle on the outer articulation with the carpopodite may 
be present or absent. 
Ischiopodite of third pereiopod hooked in the male. The hook of the first form 
is strong and subconical. 
The coxopodite of the fourth pereiopod in the male possesses a prominent rounded 
and compressed tubercle. 
First pleopods of the male of the first form (Plate XX XIX, Fig. 8) stout and 
short, reaching to the posterior margin of the coxopodite of the third pereiopods. 
They are not articulated at the base. The two parts are separated at the tips for a 
short distance, and both are curved sharply backward, forming almost a right angle 
with the basal part. Distally they are partly twisted, so that the outer part is 
directly anterior to the inner. The outer part is horny, compressed, falciform, the 
tip pointed, with a small posterior accessory point (often worn off). The inner 
part is soft, swollen at the base, and suddenly tapering to a blunt point. 
In the male of the second form this organ may be articulated at the base (in the 
case of the young) or not articulated (in older specimens). Both parts are separated 
distally for a short distance, and the outer part is soft, not horny, less distinctly 
compressed, and blunt. In the young these organs are considerably shorter than in 
older specimens. 
Annulus ventralis of the female transversely rhombiform, with a deep central 
depression and a longitudinal S-shaped fissure. Anterior and more particularly the 
posterior margins elevated. The whole anterior portion of the annulus often appears 
depressed compared with the elevated posterior margin. Where the longitudinal 
fissure passes over the posterior margin the latter is slightly depressed. In young 
females the central depression is less marked, and the margins are consequently less 
elevated, giving a rather flat appearance on the annulus. 
