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’) are 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 bifurcation 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 sharp teeth on 
its inner border. At the base of the toothed margin of the secondary 
index springs a very small process (5), 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 (0) is a little longer than 
the distal (b). 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 
(a) which is not articulated with the main portion of the hand. On its 
upper surface (turned away from the observer in the figure) is à promi- 
nent spine, like those developed along the inner margin of the normal 
hand. Articulated 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 super- 
numerary dactylus, close to its articulation with the process z, is the 
short spine characteristic of that point in the normal dactylus. The 
secondary dactylus almost equals in length the primary one, and, as in 
the example represented by Fig. 12 of the same plate, swings in a 
