of the Mole-cricket. 405 



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 conunonly 

 exerts on such occasions is very remarkable ; and, from the 

 sensation produced, may easily be supposed to be what Rcisel 

 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 de- 

 gree of hardness. 



The mole-cricket is more distinctly divisible than most other 

 insects into three separate parts, which I will call respectively 

 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 abdo- 

 men 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 

 other; and it is in consequence of the looseness of these mem- 

 branes that the animal is enabled either to separate the con- 

 nected parts to a considerable distance from each other, or 

 to contract them so closely together as to hide the interposed 

 membranes from view ; and, from the arched form of the an- 

 terior part of the thorax it can draw in its head under that 

 part, much after the manner of a tortoise. The same flexi- 

 bility of the connecting membranes enables the animal to place 

 either its head or its thorax at a considerable angle with the 

 rest of the body; a movement which is very characteristic of 

 this insect, and gives it an air of intelligence, the attitude be- 

 ing apparently that of watching, or listening. 



The head*. — All the upper part and the sides of the head 

 form a hard, thick, horny case, containing the various muscles 

 which move the jaws ; and, in order to strengthen this case, 

 two firm bars run transversely across the bottom both of the 

 anterior and posterior margin ; which bars are themselves 

 united together by a still stronger bar or beam, which runs 

 longitudinally from the middle of the one to the middle of the 

 other. There is nothing very remarkable in the parts which 



• \'iilu Plate II. figs. 1 and 2. 



constitute 



