120 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ni 



rise to the elongate, slender sternal apodemes. On the caudal side 

 the stemite becomes attenuated and merges with the base of the 

 coxites. The coxites are rather massive and laterally arched, divided 

 on the anterior face into two subsegments by a distinct suture, which, 

 in passing around to the caudal side, broadens into an articulation. 

 Both of the subdivisions of the coxae contribute to the elongate coxal 

 apodeme (fig. 4,6), which extends ventrad from both the cephalic and 

 caudal apices of the coxae, and represents a prolongation of the 

 gonocoel formed by each coxa for the accommodation of the posterior 

 gonopods. Superficially the caudal edge of the coxal apodeme appears 

 to be continuous with the mesial margin of the telopodite, but there is 

 actually no connection, and the telopodite is attached to the coxite 

 by a movable articulation. 



The posterior gonopods are rather short and robust, and the coxal 

 apodeme is half again as long as the coxotelopodite. The latter has 

 a subtriangular base resulting from consolidation of the acutely 

 angular space formed by the telopodite and coxite in such genera as 

 Arinolus and Onychelus. Distally the telopodite ends in two lobes — 

 one a subterminal, truncate, marginally fimbriate lobe on the caudal 

 side, and the other an obtusely rounded spatulate terminal lobe. The 

 apodeme is attached a short distance from the mesial end of the 

 coxotelopodite. 



The coxal lobes of the anterior male legs are illustrated in figure 

 4:,d-f. When in place, the distal third of the processes of the third 

 coxae are clasped by those of the fourth, the interlocking facilitated 

 by a subterminal notch on each of the former. In the drawing, made 

 from a slide mount, the termmal portion distad of this notch is shown 

 as bent somewhat laterad; normally it is directed caudomesiad and 

 in-line with the rest of the process. The coxal lobes of the fourth 

 and fifth legs are flat and laminate, the distomesiad comer of each 

 bent caudad and then laterad to form a slight hook. Prefemora 

 of anterior legs unmodified, but femora of each with a distinct rounded 

 projecting lobe at the base. Tarsal joints definitely flattened or 

 depressed on the dorsal surface. 



Discussion: Variation: On the basis of our moderate series of 

 mature specimens from a single locality, it is possible to determine 

 something of the individual variability in this species. Heretofore, 

 some authors have assumed that all individuals of a population must 

 be identical, and have made the slightest deviation from a known 

 standard (even from a single specimen) the basis of creation of new 

 species. We have investigated variability in several characters 

 frequently thus misused in spiroboloids. 



Segment number: Cook found that 4 of his specimens had 48 

 segments and 1 had 47. In 12 specimens at hand, we observed the 



