22 LAWSON, ON LIMAX MAXIMUS. 
The fibres, if they may be so termed, are filled with long, 
spindle-shaped endoplasts, containing clear nuclei. Examined 
under a low power, a very interesting arrangement is observed 
in connection with the contractile structure. A number of 
muscular cords are seen upon the internal surface of the heart, 
which are thus disposed :—they pass from two centres, which 
are situate about the middle of the lateral surfaces, in a radi- 
ate manner, being continuous at their extremities with the 
ordinary fibres ; and in this way they form two stellate eleva- 
tions, much resembling the muscular cords in mammalian 
hearts, and probably serving a similar purpose. The true 
auricular chamber is the sinus to which I have already 
alluded, but it is not contractile. The heart gives about twenty 
pulsations in the minute, each contraction being succeeded by 
a dilatation, and then an interval of repose following ; during 
the period of rest the sector-like expansion is gradually fill- 
ing and becoming convex; on the moment of the heart’s 
dilatation, by the tendency to vacuum occasioned, it is emptied 
of its contents, and then, contraction ensuing, the blood is 
rapidly driven through the arteries. The arterial system 
consists in the aorta, with its branches and their numerous 
divisions. The aorta arises from the apex of the heart, and 
on attaining a length of + inch it divides into two branches, 
measuring each =; inch in diameter, which continue together 
for a distance of + inch till they reach the intestinal fold ; then, 
both having crossed the gut, one branch becomes recurrent, and, 
passing beneath the intestine,runs downwards and forwards pa- 
rallel with the rectum and beneath the generative organs, heart, 
and pericardial gland, and becomes lost in supplying the gullet 
and organs of the head. The posterior branch passes backwards 
towards the stomach, and in this course gives off about twenty 
branches to the intestine and liver, the intestinal branches 
being given away distinctly, and passing over the latter organ 
to their destination. These vessels divide and subdivide ex- 
tensively, and form the most exquisite ramifications upon the 
alimentary canal, with which they contrast very markedly, 
being themselves of a pure white colour, whilst the intestine, 
from its vegetable contents, is green. Arrived at the stomach, 
the main artery bifurcates, one branch passing backwards to 
supply the ovary and caudal lobe of the liver, the second being 
sent to the stomach and left division of hepatic gland, upon 
the inferior surface of whose lobes the most beautiful arbo- 
rescent ramifications may be observed. I am not disposed to 
coincide with the view of Erdl,* that a capillary network 
exists— 
* ‘De Helicis algire.’ Bruxelles, 
