237 
anatomy of the mole-cricket, 
blood undergoes in the several organs, changes its properties to 
such an extent, as to render it incapable of repassing through 
the pores which admitted it. I cannot of course presume to 
say that such is not the case ; and I am aware that many 
entomologists will be surprised at, and perhaps disinclined to 
listen to the opinion here advanced with respect to a sangui- 
neous circulation in insects ; but I nevertheless hope that the 
opinion will not be rejected without some previous attention 
to it. With regard to the dorsal vessel of the gryllotalpa, 
which in this, as in other insects, has been supposed to stand 
in the place of an arterial heart, I have very few observations 
to offer. It does not agree in its form with the description 
commonly given of this mysterious organ ; for though it 
diminishes in diameter as it approaches the head, this is by 
no means the case towards the other extremity of it. I have 
not yet completely succeeded in tracing this vessel to its 
anterior extremity ; because as it approaches its termination 
in that direction, it becomes so delicate as to have hitherto 
broken under dissection before I arrived at the extremity of 
it. Towards the opposite extremity it gradually becomes 
larger from the centre of the body, and terminates appa- 
rently in a cul de sac about the last segment but two of 
the abdomen. 
The muscles. In the gryllotalpa, as in insects in general, 
the muscles are exceedingly numerous, and usually very 
distinctly defined ; but as their form and size in different 
parts of the body may, without difficulty, be conjectured from 
the form and size of the parts to which they are appropriate, 
I need not occupy the time of the Society by enumerating or 
particularly describing them. Those which move the fore 
