276 
MR. NEWPORT ON THE NERVOUS AND CIRCULATORY SYSTEMS 
body in each segment, are given off near these orifices. The heart is inclosed in a 
delicate membrane, which excludes it from the surrounding structures. This cover- 
ing ought certainly to be regarded as a 'pericardium, and not as an auricle, as sup- 
posed by Straus. The anterior chamber of the heart {f) is situated in the second 
segment (1.), and descends on the oesophagus at the junction of that part of the ali- 
mentary canal with the cardiac extremity of the stomach. It is there divided into 
three trunks of nearly equal size ( p,q ). Two of these pass, one on each side (p), 
around the oesophagus, and unite beneath it ; thus forming a vascular collar around 
this part of the alimentary canal, as was first seen by Mr. Lord in the Seolopendra ; 
while the other proceeds for a short distance and then gives off a second pair (u) of 
vessels, and afterwards a third (v), all which inclose the oesophagus, thus forming 
three vascular collars around this structure, very similar to those which encircle the 
alimentary canal in some of the Annelida. 
The first of these lateral arches is of great importance in regard to the development 
of the vascular system. I propose therefore to call them the aortic arches. In Spi- 
rostreptus these are divided into two branches, the posterior of which surrounds the 
oesophagus to form the great median vessel of the abdomen, while the anterior passes 
forwards and downwards by the side of the oesophagus to the large mandibles, giving 
off at the same time a large branch that enters the head, and seems to be given to 
the inferior labium. The other two branches which surround the oesophagus give 
vessels to the inaxillee, and the middle trunk is carried forwards to the brain, beneath 
which it passes and terminates in the antennae. 
In all the lulidae the heart gives off in each moveable segment of the body two 
pairs of arterial branches, which have not hitherto been demonstrated in Myriapoda. 
These vessels, which I regard as the systemic arteries, I shall describe more parti- 
cularly in Seolopendra (figs. 18 and 19. h ). They proceed from the under surface of 
the posterior part of each chamber, and passing outwards in the course of the lateral 
muscles, as noticed in a former paper, distribute themselves to the sides of the body, 
to the viscera and to the organs of generation, thus indicating the existence of a com- 
plete system of arterial vessels, even in these low forms of the Myriapoda. 
In this general structure of the circulatory organs in these vermiform Articulata, 
we perceive a shadowing out of the great circulatory organs of the higher animals. 
The ventricular heart, with its aortic arches and great descending aorta, is rudely 
sketched in this many-chambered great dorsal vessel or heart of the Myriapod, with 
its lateral arches uniting below the oesophagus to form the great channel for the 
blood to the organs of locomotion and sides of the body, a structure of which the 
type of formation is continued uninterruptedly, but gradually increasing in com- 
plicacy and importance as we ascend through this and the other classes of the Arti- 
culata to the lower forms of vertebrated animals. 
In the observations already detailed on the nervous system of these animals, I have 
shown that each moveable segment of the body is double, and is formed originally of 
