() 
90, MEMOIRS OF THE CARNEGIE MUSEUM 
e 
immovable finger. Both impressions are always present in large individuals; in 
younger ones they are indistinct, but are always marked by punctures, which are 
much crowded, and consequently by the denser hairs implanted in them. Traces 
of the impression on the upper surface are often seen in the typical form, but that 
of the lower surface is always absent, or marked only by a slight flattening of the 
surface. These two impressions give to the hand of this variety a very strongly 
marked marginal keel or ridge. The outer margin of the movable finger possesses 
a number of irregularly placed tubercles, indistinct, and restricted to the proximal 
part in young specimens, but very distinct, and occupying about two-thirds or 
three-fourths of the margin in old specimens. ‘The longitudinal ribs of the upper 
surface of the fingers are always well developed, and there is hardly any tendency 
in older specimens for them to become obscure, chiefly in the case of the immoy- 
able finger, where this rib is always well marked on account of the strongly devel- 
oped punctures of the depression accompanying it on the outside. 
The armature of the carpopodite and the meropodite is almost identical with that 
of the typical form, but the carpopodite in old individuals is often provided with 
accessory low tubercles on the upper face. ‘The spines of the meropodite are more 
distinct and more numerous; those on the distal upper margin (generally two of 
them) well developed, even in large individuals; those of the lower margin consist- 
ing of two to six in the outer row (two are rare, found only in young ones; in regen- 
erated chele as many as eight); and sever to twelve in the inner row (as many as 
fourteen in regenerated chelt). 
All the other characters, including the color (see Plate B, Fig. 2), agree with the 
typical form. The color of the eggs (in the only specimen ever found with eggs, at 
Spartansburg) is prune-purple (VIII, 1), almost black. 
There are in the collections of the Carnegie Museum one hundred and forty- 
seven specimens of this form, all of which are from Pennsylvania, with the excep- 
tion of four, which are from Kentucky. 
DISTRIBUTION. 
LOCALITIES REPRESENTED IN THE CARNEGIE MUSEUM. 
PrNnNsyLyanta: Allegheny County, Chartiers Creek, Carnegie, (D. A. Atkinson 
coll.); Pine Creek, below Bakerstown Station, (D. A. Atkinson coll.); Squaw Run, 
near Aspinwall; Alleghany River, Sandy Creek; Alleghany River, Hulton; Little 
dull Creek, Tarentum, (A. Koenig coll.) ; Puketta Creek, (A. Koenig coll.) ; McKeen 
County, Alleghany River, Larabee; Warren County, Crouse Run, Garland; Craw- 
Jord County, Oil Creek and tributaries, Spartansburg ; small tributary of Conneaut 
