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MR. NEWPORT ON THE NERVOUS AND CIRCULATORY SYSTEMS 
branches, which are given to the brain and the organs of sense, is distributed in the 
same manner in the Scorpion. The middle branch (14.) * goes forward to the brain ( b ), 
to which it gives some very fine vessels, and then passes beneath it, to be distributed 
above the palate, on the anterior part of the head, where it is again divided into three 
small trunks (14.), above the small origin of the vagus nerve. It also forms an anasto- 
mosis, as already stated, with the divisions from the great lateral artery from the pre- 
hensile organs, and thus assists to complete avascular circle around the brain (b), the 
centre of the animal functions. The two lateral branches of the cephalic artery ( 7 .) 
pass, one on each side of the brain, giving off a large vessel ( 8 .) to the great optic 
nerve (c), with which it ascends to the surface of the head, divided into many minute 
ramifications, that supply both the tegument and the chief organs of vision (b.). After 
this the lateral cephalic artery bends inwards on the front of the nerves, to the middle 
line, on the inside of the flexor muscles of the small prehensile organs (a.), the analogues 
of the antennae, and it is then divided into two principal branches (9. 10.), having 
first given off one ( 12 .) that, passing backwards and outwards, forms two anasto- 
moses with branches from the great subcesophageal division of the artery (13.), from 
which other branches are distributed. Some of these ascend to the tegument that 
covers the muscles of the second pair of legs, while others (16.) pass downwards 
among the muscles of the thorax. The largest division (9.) of the lateral cephalic 
artery then passes upwards, and is given to the great muscles of the antenna on the 
dorsal surface, while the other enters the basal joint of the antenna on its inner side, 
and is again divided into two branches which are given to the two prehensile divi- 
sions of this organ (a.). Besides these there is a third and smaller branch ( 11 .) given 
off very near to that ( 8 .) which goes to the principal eyes. This branch in like manner 
passes upwards and inwards with the nerves of the smaller lateral eyes ( d ), which 
arise by a single trunk from the same part of the brain as those which are placed on 
the middle of the cephalothorax (c). 
Thus then in the origin, and in the uniformity of distribution of the vessels and 
nerves of the head, we are enabled to identify the small prehensile organs on the 
front as the analogues of the antennae of insects, and which, although so remarkably 
altered in form from a simple, elongated, many-jointed organ, to one of a prehensile 
character, still retain the same primary function, that of touching and feeling as in 
their less complicated structure. 
This arrangement and identification of the structures in the Scorpion serves still 
farther to illustrate that admirable uniformity of design on which all organized bodies 
are constructed. The distribution of the blood-vessels in these Invertebrata is as 
uniform in its plans, and as precise in its character, as in the blood-vessels in the 
higher animals. The large arterial trunks always accompany the principal trunks 
of the nerves, especially at their origin from the brain and cord. So likewise the 
arterial vessels invariably exhibit a strong fibrous texture, more especially those which 
* This branch is very frequently absent in the Scorpion. 
