260 BULLETIN OF THE 



chela -with a supernumerary dactylus articulated with the lower face of 

 the hand. The dactylus is lost. 



Plate I. Fig. 13 (right chela). — This specimen, like the last, is didac- 

 tyle. The two dactyli [a, a') ai'c here articulated with the hand side by 

 side ; both are thrust to one side, so that they do not close against the 

 index finger. The index itself shows a tendency to duplication ; first, 

 by a slight bifui'cation at the end ; secondly, in the alteration of the 

 tooth-bearing edge into a flat surface, bearing a row of teeth on each 

 margin, directed toward the dactyli, but not met by them on closure. 



One can easily believe that this is a congenital monstrosity, while 

 most if not all the others on the plate are more naturally explained as 

 malformations arising from injuries received after moulting. 



Plate I. Fig. 14 (right chela). — A severe injury to the hand has re- 

 sulted in the growth of a process (c) from near the base of the index, 

 which duplicates the index. It is curved downward and inward, under 

 the lower face of the primary index, and furnished with shai*p teeth on 

 its inner border. At the base of the toothed margin of the secondary 

 index springs a very small process (6), which shows a line of very minute 

 teeth on its inner border, and seems to be a rudimentary third index. 

 The dactylus does not meet the primary index when the claw is shut. 



Plate I. Fig. 15 (left chela). — The dactylus is here bent upward and 

 outward at a right angle, at a point midway between the base and the 

 tip. Two finger-like processes {b, b') arise near one another from the 

 bend of the dactylus. Of these the proximal {b) is a little longer than 

 the distal (//). Both lie in the normal trend of the dactylus, and pre- 

 sent a row of teeth directed towards the teeth of the distal end of the 

 index. When the dactylus is closed, however, the teeth of neither of 

 these processes exactly meet the teeth of the index, but fall on each side. 



Plate I. Fig. 16 (left chela). This specimen resembles Fig. 12 of the 

 same plate. From the inner and lower part of the hand arises a process 

 (x) which is not articulated with the main portion of the hand. On its 

 upper surface (turned away from the observer in the figure) is a promi- 

 nent spine, like those developed along the inner margin of the normal 

 hand. Articidated with the distal extremity of this process is a long, 

 curved, pointed, toothless segment (a'), which is an imperfectly devel- 

 oped duplication of the dactylus (a). On the upper face of this supcr- 

 niwncrary dactylus, close to its articulation with the process x, is the 

 short spine characteristic of that point in the normal dactylus. The 

 secondary dactylus almost ecpials in length the ])rimary one, and, as in 

 the example represented by Fig. 12 of the same plate, swings in a 



