7o A. B. DAWSON. 



On examining the more posterior prong of the compound 

 meropodite, we find that the next distal segment, i.e., the extra 

 carpopodite (C. ' + ") is morphologically double. It is more 

 than twice as large as the corresponding segment (C.) of the 

 primary claw and bears on it supper surface two groups of spines 

 separated by a shallow longitudinal groove. On the end of the 

 massive carpopodite is the large double protopodite (P. ' + "). 

 This segment is incompletely divided, with the separation 

 extending only as far as the region on a level with the bases of 



D. I. 



D" 



FIG. i. (One half natural size.) Male lobster possessing an abnormal right 

 chela consisting of a primary nipping claw plus a double extra "crusher." C., 

 primary carpopodite; C.' * " , double extra carpopodite; D., primary dactyl; 

 D.', D.", two extra dactyls; /., primary index; /.', /.", two extra indices; Is., 

 ischiopodite; M., primary portion of meropodite; M .' + ", extra portion of 

 meropodite; O., conical protuberance on double protopodite; P., primary proto- 

 podite; P' + " (P omitted in reproduction), double extra protopodite; S., scar on 

 left chela. 



the indices (/. ', /.") Opposing the indices are two well de- 

 veloped movable dactyls (D/, D."). The two partially sepa- 

 rated chelae are almost exact mirror images of each other. The 

 dactyls and indices are practically identical and the dentition of 

 both consists of heavy tubercle-like teeth. There are no tactile 

 hairs. 



Each segment of the double extra claw was decidedly larger 

 than the corresponding portion of the primary claw, but the 

 entire "triple" appendage barely equalled the left nipping claw 

 in weight. The long axes of the double appendage and primary 



