104 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



claw is closed the dactyl is not in normal opposition, but crosses 

 over the upper face of the index. It is also dentated with the 

 crusher type of teeth. 



From the smooth or morphologically dorsal border of the dactyl 

 arises two extra spurs or processes (D'R', D'L') which practically lie in 

 the longitudinal dorso-ventral plane of the claw. One of the borders 

 of each of these two abnormal processes is toothed, and the spatial 

 relations are such that the toothed margins are turned toward each 

 other, while the opposite smooth borders are turned away from each 

 other. The character of the dentition is such that traces of " periodic 

 sequence " may be seen, i. e., teeth are arrayed in groups (p) charac- 

 terized by larger prominent teeth, with smaller teeth intercolated 

 between them. (See Scheme of Stahr, '98.) Along these dentate 

 margins are tufts of tactile hairs (h) . With respect to dentition and 

 the presence of tactile hairs, therefore, these two processes seem to 

 resemble a "nipper" more than a "crusher" type of claw. The 

 general form of the remaining part of the dactyl, together with the 

 fact that it is dentated with the crushing teeth characteristic of the 

 opposing index, clearly shows that D is the original or normal dactyl, 

 and D'R', D'L', the extra or abnormal parts. I have indicated these 

 two processes as D'R' and D'L' because, as will be shown in a later 

 discussion, according to Bateson's principles, these two abnormal 

 parts are to be interpreted as a complementary pair of extra right 

 and left dactyls. 



This specimen, together with No. 4, is preserved in Mr. Cartland's 

 collection of curios at Pemaquid Beach, Maine. 



Specimen No. 2. Fig. 2 (Left Chela). 



The propodite or index (I) of this chela is of the normal "nipper " 

 type. Apparently the only scar upon it is an indentation on its 

 lower surface, (indicated by the dotted line (a) in the figure). The 

 dactyl (D) is bent dorsally upward at an angle of about 45 degrees 

 from its normal position; otherwise it deviates but slightly in posi- 

 tion and moves in the normal plant of motion. The teeth are of 



