NO. II LARVAE OF THE ELATERID BEETLES GLEN 29 



from 8 to 14 hairs ; without "armature" ( = "scansorial hooks" auct.) ; 

 anal aperture (a) Hnear and median. 



KEYS AND DESCRIPTIONS 



In using the keys and descriptions it is suggested that the following 

 points be kept in mind: (i) The common structural differences 

 between young and mature larvae of the same species; (2) the gen- 

 eral dependability of the various taxonomic characters; and (3) cri- 

 teria by which to appraise the adequacy of larval descriptions. 



The characters presented in this study were taken from mature or 

 nearly mature larvae wherever such were available. With less mature 

 specimens certain structures will be found in relatively smaller num- 

 bers, e.g., setae, tubercles, denticles, and pits ; and these and other 

 structures in relatively smaller size, e.g., grooves, impressions, and 

 small sclerites such as in a divided prosternum ; v/hereas in very 

 immature larvae some structures, especially the nasale, caudal notch, 

 and urogomphi, may be of a quite different character. The number 

 of larval instars through which individuals pass is known to vary so 

 widely within a single species (Strickland, 1939) that no attempt has 

 been made to determine or to suggest the relative maturity of the 

 specimens examined. However, the key characters used are believed 

 to hold for larvae of a considerable range of maturity, at least for 

 all specimens that are more than half grown. 



Every structure has potential taxonomic value. However, certain 

 structures repeatedly have proved to be important, whereas others 

 rarely have mattered. Differences in size and shape of definite sclerites 

 such as the frontoclypeal area, prosternum, and pleurites are useful 

 and entirely reliable features, whereas "sensory" structures such as 

 pores, minute setae, and various sensilla are highly variable and only 

 rarely are of taxonomic importance. Characters that are commonly 

 used are briefly discussed below. 



Sise is a useful supplementary character, especially if a very large 

 specimen is encountered. However, it must be used with considerable 

 care because a shrunken larva might measure as much as one- fourth 

 longer when fully distended, and many half-grown larvae would be 

 within the size range of several species. 



Body form has taxonomic value, but in the Lepturoidini many 

 species have large lateral membranes that may be infolded or dis- 

 tended, thus changing the general shape of the specimen and im- 

 pairing the practical value of the character. However, some species 

 are normally flattened, others typically cylindrical ; some are relatively 



