ATOPETHOLID MILLIPEDS — HOFFMAN AND ORCUTT 



107 



family. Unfortunately, none of the available material of the other 

 species was preserved in a way to keep the internal tissues in good 

 condition, but in the Eurelinae, at least, the gonopod muscles appear 

 to be much the same as here described. The similarity in skeletal 

 parts of the other groups permits the inference of essential muscular 

 correspondence. The only previous notice of musculature in an 

 atopetholid is in the paper on Atopetholus michelbacheri by Verhoeff 

 (1938), but his drawings are so diagi-ammatic and vague as to be 

 totally useless. In the absence of detailed studies on species in other 

 families, and in anticipation of much variation in arrangement, we 

 refrain from submitting any tentative nomenclature at this time and 

 use a numerical symbolism in designating the different mmscles and 

 describing their functions. 



Figure 2. — Male gonopods of Atopetholus angelus in caudal aspect: a, anterior gonopods 

 with all muscle tissue removed to show internal structure characteristic of the family; 

 b, c, two views of the gonopods with various muscles removed in c to show underlying 

 details; d, left side of gonopods with posterior gonopod withdrawn from the gonocoel, 

 showing its exclusive muscles. Abbreviations: C, coxite; CXA, coxal apodeme; ST, 

 sternite; STA, sternal apodeme. Numerical muscle designations are discussed in the 

 text, p. 108. 



