COCKROACHES 9 



thing. They are a great nuisance on board 

 ship, where they are said to gnaw the skin 

 and nibble the toe-nails of sailors. Hardly 

 any animal or vegetable substance is absent 

 from their menu. It is said that they will even 



Fig. 3. Mouth appendages of Periplaneta (magnified), a. Man- 

 dible. B, First maxilla : 1, cardo ; 2, stipes ; 3, laeinia ; 4, galea ; 5, 

 palp. O, Right and left second maxiUae fused to form the labium : 

 1, submentum ; 2, mentum ; 3, ligula, corresponding to the laeinia ; 

 4, paraglossa, corresponding to the galea ; 5, palp. (From Latter.) 



devour bed-bugs, and that natives on the 

 African shores, troubled by these semi-parasites, 

 will beg cockroaches as a favour from sailors 

 in passing ships. 



The mandible (Fig. 3), with its strongly 

 toothed surface, is capable of biting and 

 grinding into fragments a very varied diet. 

 The food is moistened by the secretion of 

 the salivary glands, which is capable of con- 



