262 
MR. NEWPORT ON THE NERVOUS AND CIRCULATORY SYSTEMS 
situated at a great distance backwards in the cord, but not in the segments to which 
their nerves are distributed. These ganglia also have moved forward, and each is in 
a segment anterior to that which they supply with nerves. This shifting of the gan- 
glia has also extended to those in the caudal region (13. 14. 15. 16.), each of which 
has moved forwards and is situated near the articulations of the joints of the tail, one 
in each of the first four basilar joints. 
The distribution of the nerves to the legs affords an interesting illustration of the 
uniformity of plan in the distribution and use of similar structures in all animals. 
The great claw (/) of the Scorpion is formed by an arrest of development of the three 
tarsal joints (1. 2. 3.) that have coalesced into one large hand; but the finger-like di- 
gitations of this hand ( k ), which exist in the true organs of locomotion as minute 
claws, have become excessively developed, to form the two powerful fingers of the 
claw, as is proved by the manner in which the nerves are distributed. The great 
nerve of the limb in the other extremities is always divided into two branches imme- 
diately before or after it has entered the second joint of the tarsus (2.), and these are 
given separately along each side of the under surface of the tarsus to the two minute 
claws, exactly as the nerves are distributed to the digitations of the hands and feet of 
Vertebrata ; and it is precisely in the same way that the nerves are distributed to 
these great claws in the Scorpion. But further evidence of the beautiful uniformity 
of design is afforded in the distribution of these nerves to the tarsi. As each division 
of the nerve is passing along the under surface of the last joint of the tarsus it gives 
off a distinct nerve to each of five spines (3.), which are arranged in a series on each 
side of the under surface of this joint of the foot, on which joint the animal usually 
rests. Can it be doubted that these nerves are to supply the rigid spines with sensa- 
tion and a power of feeling, as this part of the foot is so constantly employed in 
touching and examining the objects over which it passes? The extremities of the two 
divisions of the nerves to the tarsus are extended into the minute claws {k) and termi- 
nate at the base of the nail, having first given off, on each side of the claw, a small 
branch to the muscles. 
The nerves that pass backwards from the thorax into the abdomen continue distinct, 
and are given separately (6. 7. 8. 9.) to the respective segments. Immediately each nerve 
enters its proper segment it divides into two branches ( p , q) ; one of these ( p ) passes 
outwards in the anterior part of the segment, across the front of the branchia, and 
near the margin of the ventral plates this also is divided into two branches, one of 
which ascends to the dorsal surface of the segment, while the other passing back- 
wards in front of the branchia (s) is given to the sides. The second branch ( q ) of the 
main trunk passes backwards in the segment behind the branchia, and gives off some 
ramifications to the muscles (r) on the ventral surface, and some are distributed over 
the branchia (/, m, n, o ). This second branch of the great trunk is itself a separate 
nerve, the analogue of the respiratory nerve which exists so distinctly in all the My- 
riapoda, more especially in the Scolopendra and Lithobius. The aggregation of origi- 
