272 



BULLETIN OP THE BUREAU OF FISHERIES. 



cracker, as in this case, and in giants the difference is sometimes striking. The dry shell 

 of this crusher is so dense and strong that it will bear the weight of a man of average 

 size without giving way. The measurements of these claws are as follows : 



Crushing claw: 



Length propodus inches 



Greatest breadth do. . 



Greatest girth do. . 



Contents cubic centimeters 



Weight of shell (8X oz) grams 



Toothed forceps: 



Length propodus inches 



Greatest breadth do. . 



Greatest girth do. . 



Contents cubic centimeters 



Weight of shell (4>i oz.) grams 



sy2 



680 

 235 



320 

 116 



The armature of this cracker claw (fig. 2 and 3, pi. xuii) is typical and does not 

 essentially differ from that found in giant lobsters weighing upward of 25 founds. 



Fig. 25. — Armature of right crusher of female lobster 35 mm. long, and at approximately the tenth stage, 

 showing origin of "molars" by fusion of spines. The proximal tubercle of the propodus ip (Z.)) is de- 

 rived from the lock spine, while the distal (d) is composed of a fused mass of over a dozen teeth, embrao* 

 ing the whole of period n, and part of m. l.ength of claw 14.5 mm. 



As in their case also the blunted end of the dactyl meets the big distal "molar" of 

 the propodus, which, in the Belfast lobster, is worn flat and is i^ inches long by 

 iX inches broad. The dactyl in the slenderer claw is considerably longer, and as 

 noticed above in mammoth lobsters the toothed forceps tends to surpass the crusher in 

 length. 



Since writing the preceding paragraph I have had the opportunity of reexamining 

 the New Jersey lobster, which holds the record for size and weight (see no. 9, table i), 

 and find that the great claws which here reach the extreme known development of 

 such organs, conform to the types already described and to conditions met with in mam- 



