104 PROCEEDINGS OF THE NATIONAL MUSEUM vol. m 



are strongly developed and may be carried out beyond the caudal 

 edge of the metazonite in the form of acute, upturned spinules. 

 Whether such modification is generic or only specific in value remains 

 to be determined; it recurs in various other spiroboloid famihes in 

 Central America and elsewhere. 



With few exceptions, the ozopores open just in front of the second 

 segmental suture, and shghtly below the level of the lateral longitu- 

 dinal suture. Species of the subfamily Arinohnae, so far as is known, 

 differ in that the pore is on the caudal side of the suture and thus 

 opens in the metazonite. This modification is almost certainly an 

 evolutionary specialization, as it seems to occm' only in forms that 

 are speciahzed in other respects as well. 



Male gonopods : The conformation of the male genitalia is basically 

 uniform in most of the genera. Most diagnostic for the family are 

 the combined features of a small transverse sternite and elongated 

 coxal apodemes of the anterior gonopods, and the somewhat diminu- 

 tive, two-jointed posterior gonopods. On the basis of the material 

 studied in this as well as other sph'oboloid families, the musculature 

 of the gonopods appeal's also to be characteristic of the group. 



Details of the sclerotized parts of the gonopods can be appreciated 

 only from material that has been cleaned of muscle tissue after 

 removal from the body of the specimen. Strong caustic solutions, 

 with heating, quicldy macerate the tissue, which then can be picked 

 off with fine-tipped forceps. The importance of examining the 

 gonopods in this way cannot be overemphasized. 



The sternite of the anterior gonopods is represented in all the 

 genera, usually as a narrow, sub transverse sclerite that is more or 

 less arched at the middle, presumably to facihtate passage of the 

 coelomic cavity. At the lateral ends the sternite is produced proxi- 

 mally into elongate sternal apodemes, the homologs of the functional 

 tracheal apodemes of the tj^pical generalized diplopod sternite. The 

 gonopod apodemes, however, are closed tubes, and function only for 

 muscle attachment; they tend to be short and slender, normally 

 curving shghtly mesiad. Beyond the origin of the apodemes, the 

 sternite is curved caudolaterad around the base of the coxite and is 

 usually coalescent with it. In Comanchelus hubrichti (fig. Q,b) this 

 fusion is incomplete; the tip of the sternal extension remains free of 

 the coxite margin, probably reflecting a primitive condition. 



In general, the coxites are firmly attached to the lateral extremity 

 of the sternite, leaving a more or less membranous, unconsolidated 

 area along the middle of the gonopod. This condition is characteristic 

 of the subfamily Eurelinae, where a distinct intercalary thickening 

 of the membrane between the coxites has taken place — a develop- 

 ment here referred to as the vinculum (Lat., a buckle) — and clearly 



