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BULLETIN 67, UNITED STATES NATIONAL MUSEUM. 



or rotten wood, etc. The millipedes, or Diplopoda (fig. 188), are very 

 remote from insects. They have a hard, round, or flattened body of 



many rings, and each ring bears two pairs of 

 legs. Their mouth-parts are weak, and they 

 feed on vegetation or decaying matter. None 

 of them can bite. 



Most of the directions given for collecting 

 insects apply to these groups. They are 

 treated as alcoholic insects, but not so much 

 apparatus is needed. A net is useful ; a fine 

 forceps is necessary, and a sieve net is very 

 handy to get the small forms. All of these 

 should be collected in vials of alcohol of 

 about 60 per cent and later put in 75 or 80 

 per cent alcohol, with a little glycerin. The 

 mites can be obtained by sifting leaves and 

 moss, and under boards, in fungi, and on 

 foliage. The egg sacs or cocoons of spiders 

 can be collected in pill boxes. In collecting 

 spiders one should learn to distinguish the 

 adults from the young. The mature male 

 has the tip of the palpi developed into a 

 complicated accessory genital apparatus. 

 The mature female has the vulva or genital 

 opening exposed at the base of the venter 

 of the abdomen. Spiders not having either 

 of these two characters are immature. It 

 is useful to collect the immature stages of 

 spiders, but if one does not know the differ- 

 ence he is apt to gather a great number of 

 young specimens. When one finds a spider in the young condition he 

 may be able, by visiting the spot later, to find some adult specimens. 

 Most Arachnids and Myriopods should be kept in corked vials of 

 alcohol with a little glycerine, just as alcoholic insects. Empty 

 cigar boxes or Marx trays, made for a double row of vials, are suit- 

 able for arranging collections. 

 The labels should always be 

 inside of the bottles. Many 

 mites are better when mounted 

 in balsam or glycerin on slides. 

 This is done as for mounting small insects. 

 be killed in hot water or acetic acid 

 of insects. 



Fig. 187. — The house centipede, 

 scutigera forceps. 



Fig. 188.— A millipede, Cambala annulata. 



Many of these should 

 The slides may be kept as those 



