THE DIPLOPOD FAMILY STPtlAKIID^. 

 By O. F. Cook, 



Custodian of Myriapoda. 



The following descriptions and figures were prepared several years 

 ago, before the publication of the posthumous papers of the late Mr. 

 Bollman. Since that time tilriariu lias been recognized as the type not 

 only of a family but of a distinct suborder. The structural similarities 

 of LyHiopfffaliim, dhordenina, and Striaria are so great that the infer- 

 ence of aflinity is unavoidable; but it is equally plain that the genera 

 mentioned represent diverging lines, and no forms are yet known 

 which can be looked upon as connecting the tlirce groups. xV^ccordingly, 

 the suborders Lysiopetaloidea, Chordeumatoidea, and Striarioidea have 

 been arranged under the ordinal name C<jelocheta, but as no formal 

 characterization nor synopsis including this order has been published 

 these deficiencies are supplied below. 



ANALYTICAL KKY TO THK OUDKKS OF CiriLOGNATHA KNOWN KKOM THE INITED 



STATES. 



Body composed of uot more than VA flistiiict segmftnts; males have legs at the 

 posterior end of the body njodifierl to assist in oo|iulation : Order OxiscoMOKi'irA. 



Body <;oini»osed i>i at least 19 segments; males have one or hoth pairs of legs of 

 the seventh segment modified to assist iu copulation, the posterior legs' heing 

 normal 



Body composed of 20 (rarely 19) segments, which are complete chitiuous rings, 

 all the primitive sclerites being comj)letely fused, even the sutures Ix-ing obliterated : 

 Order Mehociikta. 



Body coi/iposed of 30 (rarely 2fj or 28) segments and al>ove; fusion of primi- 

 tive sclerites less complete, at least the pedigerous lamiuK? separated by distinct 

 sutures 



Males with eight pairs of normal legs iu front of the 4-.>-jointed copulatory legs, 

 which are the posteiior pair of the seventh segment and the anterior pair of the 

 eighth; head and mouth-jjarts greatly reduced, the latter suctorial rather than 

 manducatory: ()rih;x Colohoonatha. 



Males with seven more or less normal legs in front of the seventh segment, of 

 which the anterior pair, and usually both pairs, are transformed into simple or 

 2-jointed <opulatory organs; head large, the mouth-parts well develoijed and 

 distinctly manductory 



Proceedings U. S. National Museum, Vol. XXI— No. 1 169. 



G67 



