ORTMANN: THE CKAWFISHES OF THF, STATE OF PENNSYLVANIA 409 



of llie western form is generally shorter. While in the eastern form it is at least one 

 and one-half times as long as the palm, in the western form this relation is the 

 maximum, and is due to a proportionally heavier and stronger development of the 

 palm as compared with the fingers. (This does not hold good for regenerated 

 cheliu, in which the dactylopodite always is considerably longer in proportion to 

 the palm.) 



The tubercles of the cutting edge of the dactylopodite are slightly different in 

 both forms. In the eastern the third or fourth is generally much larger, and, just 

 before it, there is a gap, as if one tubercle were suppressed. This produces a distinct 

 excision at the base of the finger, which is always more or less marked, even in 

 rather young individuals, so that the fingers always appear gaping at the base (PI. 

 XL, Fig. 6). In the western form the fourth or fifth tubercle is larger than the 

 rest, but there is no distinct gap anterior to it, the three or four proximal tul)ercles 

 being ratlier equidistant. They decrease slightly in size from the first to the fourth, 

 so that a slight emargination is indicated. I'ut this emargination and the large 

 tubercle following it are well <listinguishable only in larger individuals ; in younger 

 specimens they are rather indistinct, or entirely wanting, so that the basal gaj) is 

 absent, and the fingers are in contact all along their edges. 



The differences in the relation of dactylopodite to palm, and in the tuljercles of 

 the dactylopodite, give to the whole chela of the western form a difierent aspect, 

 the hand appearing rather more massive with shorter fingers. (See PI. XL. Figs. 

 G and 7.) 



8. The co/o/'.s in western specimens are more vivid, and with more contrast. 

 Eastern specimens are more uniformh' russet or olive-green, with no oil-green at the 

 l»ase of the fingers, while the latter tint is very characteristic of the western form, at 

 least in specimens of a certain size. Old western specimens, when fresh, are ratlu-r 

 brilliantly colored. 



1 think 1 am able to recognize and t(j distinguish ea.stern and western speci- 

 mens, chiefly by the help of the characters of the chela?, if the latter are normally 

 developed; but I do not know whether it would be advisable to distinguish lioth 

 forms l)v varietal names. Tlie latter maybe necessary in future, when the forms of 

 C. dioyenes from the regions west of Pennsylvania have been more clo.sely studietl. 

 I think I am able to see certain differences in the western specimens in our collec- 

 tions, but the material is too poor to be sure of it. 



No remarkable freaks or malformations have been observed in this species, with 

 the exception of a few color variations. They are the following: 



1. In I'ern Hollow, Pittsburgh, a specimen was found in a stagnant [lool, (i to 



