EXTERNAL ANATOMY OF INSECTS. 439 



rove-beetles (Staphylinidce), as in Ocypus, Staphylinus, 

 and Creophilas Kirby. In the first of these it is a curved, 

 narrow, white, subdiaphanous, submembranous, or rather 

 cartilaginous piece, proceeding from the upper side of 

 the base of the mandible a ; in the second it is broader, 

 straighter, and fringed internally and at the end with 

 hairs ; and in this at first it wears the appearance of be- 

 ing attached laterally to the mandible under the tooth b , 

 but if closely examined, you will find that it is separate : 

 in Creophilns maxillosus it is broader. This is the part 

 I have named prostheca. It is perhaps useful in prevent- 

 ing the food from working out upwards during mastica- 

 tion. 



5. Maxilla; c . The antagonist organs to the mandible 

 in the lower side of the head, are the under-jaws, or max- 

 illa — so denominated by the illustrious Entomologist of 

 Kiel. Linne appears to have overlooked them, except 

 in the case of his genus Apis, in which he regards them, 

 and properly, as the sheath of the tongue. De Geer 

 looked upon them in general as part of the apparatus of 

 the under-lip or labium; and such in fact they are, as 

 will appear when we consider them more particularly. 

 Fabricius has founded his system for the most part upon 

 these organs, the principal diagnostic of ten out of his 

 thirteen Classes (properly Orders) being taken from them; 

 and in the modern, which may be termed the eclectic, sy- 

 stem, although the Orders are not founded upon them, 

 yet the characters of genera, and sometimes of large 

 tribes, are derived from them : and as they appear less 



» Plate XIII. Fig. 7. c". 



b Oliv. Ins. no. 42. Staphyl'mus. t. i.f. 1. b. 



c Plates VI. VII. XXVI. tl'. 



