anatofny of the mole-cricket, 209 
bility of repelling moisture ; which capability is so remark- 
able, that when the insect is plunged under water, it appears 
as if cased in silver, or some bright metallic covering : this 
appearance being evidently derived from a stratum of air, 
interposed between its body and the surrounding liquid. This 
down not only serves to repel the adhesion of any moist sub- 
stance to its body, but also facilitates the motion of the animal, 
by lessening the degree of friction which would otherwise 
take place ; and it is owing to the same circumstance that 
there is an unusual degree of difficulty in retaining a sure 
hold of the insect, even when dead ; but more especially when 
alive, and struggling against detention. The degree of force 
which it commonly exerts on such occasions is very remark- 
able ; and, from the sensation produced, may easily be sup- 
posed to be what Rosel says it is, equal to the counterpoise 
of two or three pounds. The skin or covering of the insect is 
in some parts nothing more than a thin membrane ; in other 
parts it resembles soft leather ; and sometimes equals horn 
or even shell in its degree of hardness. 
The mole-cricket is more distinctly divisible than most 
other insects into three separate parts, which I will call re- 
spectively the head, the thorax, and the abdomen ; although 
I am aware that the anterior part of that which I call the 
abdomen is usually considered as a part of the thorax. Of 
the three parts above-mentioned, the head is not above one- 
twelfth the length of the whole body ; the thorax three- 
twelfths ; and the abdomen eight-twelfths. 
■ The head is united to the thorax, as the thorax also is 
united to the abdomen, by means of a loose membrane, which 
envelopes the muscles that pass respectively from one to the 
