MEMOIRS OP THE NATIONAL ACADEMY OF SCIENCES. 



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claw. (1) With respect to the first point, we meet with a perfectly graduated series between the. 

 two extremes (Figs. 11, IS, PI. xxn, Figs. 4, PI. xxin). (2) The same is true, of the relative lengths 

 of the atitenual spines, the scale, and peduncle (Figs. 11, 13, 14, PI. xxn). In Fig. 11 there is no 

 evident scale and the spines are nearly equal. In Fig. 14 the spines are markedly unequal, and 

 there is a rudimentary scale. In Fig. I.'! this scale is further developed. (.'?) Great variation is seen 

 in the small chela. The fingers of this claw may each end in two or three prongs, or one in two, 

 the other in three, or the tips of the fingers may be simple or merely notched. The tuft of peculiar 

 seta 1 on the dactyle may be reduced or wanting. (4) Various stages between the long and short 

 carpus arc observed, and (5) slight variations not easily described are constantly seen in the relative 

 size, shape, and other characters of the largo chela. 



These variations are shown in a general way in Table I. (For detailed measurement, v. Table 

 II.) The fifteen cases here recorded were selected from upward of seventy-five, in a large number 

 of which the variable parts were drawn for more careful comparisons. 



TABLE I. Showing variations in Alphcus saulcyi and the intermediate stayes between the varieties 



brevicarpus and longicarpus. 



S. Mis. 94- 



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