THE LOBSTER. 
349 
analogy with the human stomach, and not because the anterior 
part is near the lobster’s heart, which it is not. In the cardiac 
part is a complex, calcareous, grinding apparatus, moved by 
special muscles, and commonly known as the lady in the 
lobster,^'’ In the pylorus are fine hairs, which act like a strainer. 
A long and straight intestine continues from the stomach back- 
wards, and terminates beneath the telson. 
There is a csecal salivary gland near the mouth, and the liver 
is a large ramified structure, not solid like our own, and there 
is nothing to represent a pancreas. 
All the muscles of the body, even those of the intestine, are 
composed of striated fibres. 
The blood is a slightly dusky fluid containing numerous 
nucleated corpuscles, which change their form with remarkable 
activity. 
The heart is situated in the dorsal part of the thorax, and if 
the hinder half of the dorsum of the carapace be removed during 
life, it will readily be seen pulsating. It consists of a single 
chamber or ventricle suspended in a large sac, unfortunately 
named the ^pericardium, though it is quite a distinct structure 
from the part so named in man. The ventricle has three pairs 
of apertures so closed by valves as to readily allow the entrance 
of blood from the pericardium, but to hinder its regurgitation* 
It has three other pairs of openings, each of which is the com- 
mencement of an arterial trunk conveying blood all over the 
body. These arteries have valves at their origin, and ramify 
and end ultimately in capillaries, which open into what are 
called venous sinuses, because they are channels without any 
definite shape. The venous blood collects in a great sternal 
sinus, and thence passes up into the gills to be oxygenated, after 
which it proceeds to the pericardium to find its way into th«- 
ventricle. Thus the heart propels arterial or aerated blood to 
the body — not venous blood to the gills, as in fishes. The re- 
turning blood is not redistributed through the liver as in man, 
i,e. there is no portal circulation. There are no lymphatic 
vessels. 
The breathing organs or gills are pyramidal bodies, each 
consisting of a central ascending stem with numerous horizontal 
branches, through which the blood circulates. There are twenty 
such structures on each side attached to the bases of the legs, 
and protected by the carapace as they pass up into the large 
chamber between the great bent-down thoracic pleuron and the 
true body. The gills are not ciliated, and thus require that the 
water bathing them should be incessantly renewed by other 
means. This is partly brought about by the very movements 
of the legs to which they are attached, and partly by the epi- 
podites which ascend between the gills. The main agent. 
