INSECT A. 291 



Sp. Polydesmus complanatus, Julus complanatus L v DUMERIL, Consid. gener. 

 PI. 57, fig. 2, DE GEER, Ins. vin. PI. 36, fig. 23 ; 8 lines long, i line broad; 

 31 pairs of feet. There are many foreign species of this genus ; comp. BRANDT, 

 Bulletin scientifiqm de I'Acad. de St. Petersbourg, Tom. v. and ix ; Receuil 

 deMemoires, &c. pp. 125 141 ; NEWPORT, Ann. of Nat. Hist. xm. pp. 265, 

 766 ; GERVAIS, GUERIN, Magasin de Zool. 1838. PL 240, fig. i ; (Poly- 

 desmus margaritiferus from Manilla), &c. In the male there are in the 

 seventh ring of the body, on the ventral surface, two hook-like organs 

 directed forward, and (behind them) only one pair of feet. 



Craspedosoma LEACH. Eyes distinct. (Sub-genera Craspedosoma, 

 Chordeuma, Campodes KOCH). 



Strongylosoma BRANDT. Body covered with a hard skin, elon- 

 te, round. Eyes none. 



B. Middle segments of the body composed of three parts, with 

 the ring nearly complete at the dorsum and sides, and two middle 

 ventral laminae, one situated behind the other, in whose posterior 

 margin the feet are inserted. Trizonia BRANDT. 



Julus L. (exclusive of some species). Body elongate, cylindri- 

 ., covered with hard skin, with segments not marginate. Feet 

 merous. 



Sub-genera : Julus, Spirotrephon BRANDT, Spirotreptus BR., 

 Spirocydistus BR., Spiropceus BR., Spirdbolus BR., Eurygyrus KOCH, 

 Nemasoma KOCH, Blanjulus GERV., (Allajulus KOCH, no eyes), 

 Lysiopetalum BRANDT. 



Comp. on the internal structure of these animals TREVIRANDS, Vermisch. 

 Schrif. II. 1817, s. 39 47 ; SAVI, Osservazioni per servire alia storia 

 di una specie di Julus, Opuscoli scientif., Bologna, i. 1817, pp. 321 337. 

 (Julus communis SAVI, Julus varius FABR.) ; SAVI Osservaz. sulV Julvs 

 fostidissimus (Lysiopetalum fatidissimum BRANDT), op. cit. in. 1819, p. 52 ; 

 NEWPORT, On the Organs of Reproduction and the Uevelopm. of the Myria,- 

 poda. Phil. Trans. 1841. Pt. n. pp. 99 130, (the article Myriapoda by 

 RYMER JONES in TODD'S Cyclopaedia, in. pp. 551 560, contains a full 

 extract from it). 



These Insects (the Myriapods) live principally on vegetable food ; 

 some also eat dead earth-worms and small molluscs. They diffuse, 

 like many other animals of this family, an unpleasant smell which 

 in some species is very powerful ; it is caused by an unctuous fluid, 

 with acid reaction (SAVI), which is secreted in small sacs or vesicles, 

 of which there is a pair situated in each ring. TREVIRANUS erro- 

 neously supposed these vesicles to be respiratory organs, and their 



192 



