258 BULLETIN OF THE 
horn (b) resembles that of the index (a), while the teeth of the distal 
horn (c) mark it as the analogue of the index. There is no trace of 
articulation at the base of either horn. 
There are several specimens similar to this in the collection of the 
Peabody Academy of Science, Salem, and two or three in the collection 
of the Boston Society of Natural History. 
Plate I. Fig. 3 (right chela). — Dactylus (a) slightly flexed from the 
plane of the index and broken off about an inch from the tip. From 
the inner side of the dactylus, near the fracture (d), arise two toothed 
processes (6, c), directed forwards, which repeat in form the lost tip of 
the dactylus and the tip of the index. A short, blunt process, directed 
upward and forward, projects from the inner margin of the dactylus, at 
a point a little beyond the middle. 
Plate I. Fig. 4 (right chela). — Here the dactylus (a), a short distance 
from its articulation with the hand, is bent at a right angle with its 
normal trend, and thrown out from the plane of the hand so that it 
crosses the index when closed. The tip is broken off. From the un- 
toothed margin of the dactylus, near the proximal end, proceed two pro- 
cesses (b, c) at an angle of about 45? to one another, the distal one (c) 
taking the normal direction of the index. Both of these processes are 
toothed on their opposed margins, but it is noteworthy that the teeth of 
the two processes are not directed exactly toward each other, but are 
inclined a little downward, as if by attraction to the teeth of the thumb. 
It is curious to observe that the toothed margins of the index and 
thumb are beset with an uncommonly large number of stiff setze, and 
that this character is repeated in the toothed edges of the monstrous 
processes b, c. 
Plate I. Fig. 5 (left chela). — Similar to Fig. 2, but the processes b 
and c, instead of diverging from one another, cross one another near 
their tips like the index finger and thumb of the claw when closed. 
Plate I. Fig. 6 (right chela). — In this claw, unlike what we have seen 
in those before noticed, the prehensile power has not been lost, the dac- 
tylus closing accurately upon the index. Just beyond the middle of the 
dactylus springs a simple branch directed forwards at an angle of 45? 
with the long axis of the dactylus. This branch shows no tendency to 
form teeth. 
Plate I. Fig. 7 (left chela). Here the dactylus (a) is bent near the 
middle, at almost a right angle with its normal direction, away from the 
index, but is thrown very little, if any, from its true plane of motion. 
It has acquired an abnormal length, and developed two processes from 
