124 REPORT OF COMMISSIOXERS OF INLAND FISHERIES. 



graphs. For this purpose drawings (Figs. 28-31) have been made 

 of the index or propodite part of each claw to show the characteristic 

 dentition and distribution of tactile hairs. 



The original right "nipper" index (Fig. 30) is of a characteristic 

 normal type. Tactile hairs (h) are distributed in a dense fringe on 

 each side of the dentated margin and along the distal outer border 

 of the jaw. The teeth are narrow and pointed. These cutting 

 teeth are arranged in a linear series, and in a periodic sequence 

 with a formula of 1:4:3:4:2:4:3:4 for a perfect period (P).* All 

 the teeth of the propodite are included in the single linear series, 

 except a stout displaced tooth (t) about midway in the dentate mar- 

 gin, which forms the "lock" to the claw (Herrick, '05). Another 

 characteristic feature in the arrangement of the teeth is that at the 

 posterior part of the jaw the single series of teeth are shunted off to- 

 ward the upper face of the propodite in the direction of the upper 

 or outer side of (y) the joint (j) formed l)y the union of the two 

 segments of the claw. 



The original left claw (Fig. 29) is a typical normal "crusher." 

 The index or propodite part of the claw, in marked contrast to the 

 morphological characters just described for the "nipper," is charac- 

 terized by the almost entire absence of tactile hairs, only a few iso- 

 lated tufts (h') remaining near the angle of the jaw. The "stout 

 displaced tooth" of the nipper is absent. Instead of the pointed 

 cutting teeth, the jaw is dentated with broad " crushing'.' tubercles (t) 

 formed by the fusion of periodic teeth (according to Herrick, '05). 

 A normal feature in the dentition is the double row of tubercle 

 teeth iir) at the posterior part of the index. An equally typical feature 

 is that these two rows of teeth do not shunt off toward one side of 

 the joint, as in the "nipper," but are arranged along either side of 

 the median line of the jaw. 



In this lobster the propodite of the regenerated left claw (Fig. 28) 

 closely resembled the original "crusher." No tactile hairs are 

 apparent, except a few tufts (h) near the angle of the jaw. The 



♦According to the scheme of Stahr ('98) and Herrick ('05). 



