390 MEMOIRS OF THE CARNEGIE MUSEUM 



immovable finger. I'oth impi-essions are always present in large individuals ; in 

 younger ones they are indistinct, but are always 'marked liy 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 tul)ercles, indistinct, and restiicted to the proximal 

 part in young specimens, but very distinct, and occupying al)Out 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 immov- 

 able finger, where this ril) is always well marked on account of the strongly devel- 

 oped punctures of the depression accompanying it on the outside. 



The ai'mature of the cnrpopodifc. and the mernpfxViic is almost identical with that 

 of the ty])ical form, but the carpopodite in old individuals is often provided with 

 accessory k)W tubei-cles 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; tho.se of the lower margin consist- 

 ing of two to six in the outei- row (two are rare, found oidy in young ones ; in regen- 

 erated cheUe as many as eight); and seven to twelve in the iimer row (as many as 

 fourteen in regenerated cliehe). 



All the other cliaracters, including the cohir (see Plate B, Fig. 2), agree with the 

 typical foi'm. The color of the eggs (in the only specimen ever found with eggs, at 

 Spartansburg) is prune-purplc (\'1I1, ] ), almo.st 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. 



DL-^TRIBUTION. 

 LOCALITIES REl'KESENTED IN THE CARNEGIE MUSEUM. 

 Pennsylvania: Allcylicn;/ CoLditi/, ( "hartiers Creek, Carnegie, (D. A. Atkinson 

 coll.); Pine Creek, below Bakerstown Station, (D. A, Atkinson coll.); Squaw Run, 

 near Aspinwall ; Alleghany Uiver, Sandy Creek; Alleghany Uiver, Hulton ; Little 

 Bull Creek, Tarentum, (A. Koenig coll.) ; Puketta Creek, (A. Koenig coll.) ; McKccit 

 Couidij, Alleghany River, Larabee ; Warren Count //, Crouse Run, Garland ; Craw- 

 ford County, Oil Creek and tributaries, Spartansburg ; small tributary of Conneaut 



