148 PROCEEDINGS OF THE NATIONAL MUSEXJM vol. ni 



cannot be observed with accuracy, but it appears that the ozopores 

 open in the metazonites, in contrast to most other genera of the 

 family. 



The anterior gonopods are curious in having the membranous tissue 

 between sternite and coxites thrown into folds and rather heavily 

 sclerotized; mesially this tissue is either produced in the form of a 

 subtriangular vinculum or extends up between the coxae as two closely 

 appressed lobes that superficially appear to be a smgle median process. 

 The coxites appear to be subdivided by lateral sutures into two or 

 more sclerites and have occasionally been so illustrated, but this con- 

 dition is an illusion caused actually by rather pronounced grooving 

 of the surface. The internal effect of this condition is to compart- 

 mentalize the inner surface of the coxites as far as the insertion and 

 origin of the coxal muscles are concerned. Distally the coxites are 

 drawTi out mto rather elongate and distinctly lammate processes of 

 which mostly the narrow dimension is visible in anterior aspect, the 

 elongations being much more pronounced than in other subfamilies 

 of the Atopetholidae. On the caudal side, the sternal apodemes do 

 not extend mesiad as far as usual, but the coxal apodemes are similar 

 to those of other members of the family in having one edge continuous 

 with the mesial anterior edge of the coxite and the other edge extend- 

 ing up to the mesially infolded caudal portion of the coxite. The 

 telopodite is relatively large, and its distal end is likewise drawn out 

 into a slender apex, which, in Arinolus at least, is rather laminate 

 and bent distinctly caudolaterad and lies, when in situ, in the para- 

 median notch of the sympleurite of the seventh segment. Details on 

 this point are unfortunately lacking for the other genera referred to here. 



The coxites of the posterior gonopods are large and somewhat vari- 

 able in shape. The telopodite is attached as usual at the extreme 

 lateral end of a coxite, and the two conjointly form an acute angle 

 with a visible joint at the apex. In Arinolus this joint seems to have 

 some flexibility, but in Scohinomus and, presumably, Tarascolus as 

 well, the two elements of the gonopod are extensively consolidated 

 much as in Atopetholus, and the structure is more unified. The telo- 

 podite m all genera of this gi'oup is thin and flattened, with a basal 

 peduncular portion that merges distaUy mto an expanded laminate, 

 subconchoidal portion subtended on the caudal margin by a solenom- 

 erite of variable size and shape. This latter structure is one of the 

 diagnostic features of the Arinolinae, and ranges in appearance from 

 a short, probably nonfunctional knob in some Arinolus to a long 

 blade in Piedolus that exceeds the tip of the main branch and that is 

 seen to carry a seminal groove. The posterior gonopod in Scohinomus 

 is unusuaUy short and heavy, chiefly because of a shortening of the 

 telopodite peduncle and enlargement of the terminal calyx. 



