ANNELID GENTJS CAMBARINCOLA — ^HOFFMAN 367 



tion. Because of the small size of the sex organs, which are not par- 

 ticiilarh' confined by the gut as in most other species, the spermiducal 

 gland and prostate in particular are liable to considerable freedom of 

 motion in the coelom, and preserved specimens show much variation 

 in the shape of these two structures due to a difference in perspective. 

 The spermatheca seems to have a constant shape, as does the general 

 bod}' outline. The range of this species may be so limited that geo- 

 graphically influenced variability will be found negligible. 



Relationships. — There is no other species in the genus Avith which 

 demissa can be compared. C. branchiophila of the Alesochorea section 

 is knoAvn to be a gill form, and has small jaws and a cuneate body 

 form, but its sex organs are of normal size and the major parts of the 

 bursa correctly proportioned. It is difficult to derive demissa from 

 either of the other two major sections of the genus, although if com- 

 pelled to make a choice I should tentatively place it much closer to the 

 Mesochorea section as representing the culmination of evolutionary 

 tendencies in that ensemble. As this form is probably localized among 

 the high mountams of southwest Virginia, there is every reason to 

 presmiie that maii}^ other endemic species remam to be discovered, 

 and some of these may cast some light on the affinities of this curious 

 and disjunct little worm. 



Distribution. — Aside from the type localitj^, C. demissa is laiown 

 only from the following locality: 



Virginia: tazewell couxty: Bluestone River, 11.2 miles east of Tazewell on 

 U.S. Hy. 460; June 18, 1950, Hobbs and Hart (PCH 393). 



Remarks. — The possibilit}^ of any host specificity on the part of 

 this species is negated by the fact that the type series came from a 

 collection of two species of Orconectes, the other knoAvn material from 

 a collection of tvv^o species of Cambarus. Presumabl}^ the factors 

 influencing the distribution of demissa are those of simple geograph}- 

 and water conditions rather than the occurrence of the craj'fish hosts. 



I cannot, at this time, imagine what might favor the selection re- 

 sulting in the drasticall}- reduced size of the reproductive sj^stems, 

 unless it be that residence within the branchial chambers of crayfish 

 affords sur\dval with a reduced nmnber of progeny. Perhaps laiowl- 

 edge of the ecology of the species will shed some light on this interest- 

 ing evolutionary problem. 



The name demissa (Lathi, hmnble, unimposing, modest) seems 

 appropriate in view of the general form of the animal as well as its 

 very moderately scaled reproductive systems. 



Species of uncertain systematic position 



Under this heading I include two species which are known to be 

 referable to Camharincola, but which, for one reason or another, cannot 



