ATOPETHOLID MILLIPEDS — HOFFMAN AND ORCUTT HI 



atopetholids are actually somewhat larger and longer than the claws 

 of the normal postgenital limbs. It seems safe to infer that the legs 

 of atopetholids have been variously modified or specialized in different 

 genera to serve functional and less obvious needs, although the modi- 

 fications have not taken the same direction of evolution as seen in 

 other parts of the animals, particularly the gonopods. Taxonomically, 

 however, the legs afford useful recognition characters, particularly in 

 areas where two otherwise superficially similar species may occur 

 together. 



Systematic Status 



Determination of the systematic position of the Atopetholidae is a 

 matter fraught with great difficulty. Despite useful treatments by 

 Brolemann (1914) and Attems (1926), the classification of the Spiro- 

 bolida is still very unsatisfactory chiefly because no careful morpho- 

 logical studies have been made to determine the structural detads of 

 the male gonopods, upon which family groupings must largely be 

 founded, Brolemann's early study provided a fairly satisfactory ar- 

 rangement for its time, but since then the number of genera has 

 increased enormously, and in few instances have the new groups been 

 sufficiently diagnosed to enable their placement in his system. Even 

 Attems' treatment in 1926 is objectionable because of the author's 

 reluctance to recognize small genera or families. The genera that he 

 placed in the "Spirobolidae" could obviously be dispersed among three 

 or four families. These families would be small groups, of course, but 

 it must be remembered that so far only a start has been made in the 

 discovery and classification of the Diplopoda, Since 1926, as already 

 remarked, the situation has become even more acute, as evidenced by 

 the way genera have been successively interchanged from the Atope- 

 tholidae to the Spirobolidae, and vice versa, as well as the recent and 

 lamentable redescription of one of the best-known trigoniulid species 

 as a new genus in the Spirobolidae, The main reason for the prevail- 

 ing confusion lies in the fact that few workers have taken the trouble 

 to remove the gonopods from their specimens, and actually study them 

 with respect to their total structure, even though Carl inveighed 

 against this carelessness as far back as 1919, 



As the record now stands, the Atopetholidae is the only spiroboloid 

 family whose characters are well enough kno^vn to provide a basis for 

 understanding. Comparison with other established groups is therefore 

 somewhat premature, yet it will be useful to point out a few obvious 

 lines of affinity, Attems and Brolemann established a primary sub- 

 ordinal dichotomy in recognizing one group in which the posterior 

 gonopods are connected by a sternal remnant, and another in which 

 they are completely independent, the groups being recognized first as 



