REPORT OF COMMISSIONERS OF INLAND FISHERIES. 103 



The various segments of the cheliped, as shown, for example, in 

 Fig. 6, will be designated as follows: 



Dactyl (D): The first segment, i. e., counting in a disto-proximal 

 direction. 



Propodite (Pr) : The second segment. 



Index (I): The distal part of the propodite which opposes the 

 dactyl and forms one jaw of the claw. 



Carpopodite (C) : The third segment. 



Meropodite (M) : The fom-th segment. 



Ischiopodite (Is) : The fifth segment. 



Basipodite (Bs) : The sixth or basal segment (not shown in Fig. 6) . 



All these segments are united by flexible joints, with the excep- 

 tion of the last two segments, the basipodite and ischiopodite. The 

 latter two segments are fused together into one immovable piece, 

 but there is still a distinct groove marking the two segments. It 

 is always at this groove that separation occurs when^the limb is 

 thrown off by autotomy. 



B. Abnormal Chelipeds found in the Lobster. 



We will first describe the abnormal structiu"es which we have 

 obtained from museum collections or have found on lobsters taken 

 from the traps; leaving for a later section those abnormalities which 

 were experimentally obtained as regeneration products. 



1. Extra Processes arising from the Normal Dactyl. 



Specimen No. 1. Fig. 1. (Left Chela). 

 The propodite or index (I) part of this claw appears to be normal 

 in every respect, except that there are two scars (a, a") along its 

 smooth outer border; these scars may possibly have been connected 

 with the origin of the abnormalities in the remaining part of the 

 claw. The dentition of the index clearly shows that it belongs to 

 the "crusher" type of chelae. The dactyl (D) is strongly curved 

 and twisted upward from its normal plane. Consequently when the 



