ANNELID GENUS CAMBARENCOLA — HOFFMAN 



345 



out prior to a formal recognition. The problem is complicated by the 

 nearby occurrence of chirocephala which also appears to intergrade 

 with philadelphica. 



Representative specmiens of each of the three forms of this species 

 are illustrated, and material is separated appropriately in the lists of 

 specimens examined. There is little or no appreciable difference in the 

 reproductive systems. 



Affinities.^ — ^The species of the Philadelphica subgroup are all 

 closely related and by no means easy to separate. A complication is 

 introduced by the certainty that additional forms will be discovered 

 and defined, particularly in the Appalachian region. Of the named 



45 <C^ 



"^ 



Figures 43-46. — Structural details of Camharincola chirocephala Ellis. 43, Lateral aspect 

 of typical specimen, Benton Co., Arkansas; 44, dorsal aspect of jaws, specimen from 

 Benton Co., Arkansas; 45, lateral aspect of jaws, specimen from Logan Co., Arkansas; 

 46, lateral aspect of reproductive systems, specimen from Logan Co., Arkansas. 



forms, philadelphica, chirocephala, and macrodonta are most alike, and 

 future work may indeed show them to be only components of a wide- 

 ranging polytypic species. Some of the Kentucky material listed 

 under chirocephala shows a remarkable similarity in almost every 

 respect to philadelphica, and I have been able to demonstrate gradual 

 east-west clinal variation in both the jaws and spermiducal gland of 

 chirocephala. That these two species intergrade seems almost cer- 

 tain. Perhaps the establishment of an arbitrary ratio of jaw widths 

 will help define the ranges of the two, as well as their intermediates. 

 The relationships of philadelphica to macrodonta are also very close. 

 The entu'e peristomium of the latter is a good distinction between 

 well-preserved material of the two, and if present unpressions are cor- 

 rect, the smaller bm'sa (less than the spermiducal gland in diameter) of 

 macrodonta should aid in recognition of the species. C. macrodonta 

 apparently occurs in South Dakota, philadelphica in Wisconsin. 



