ANNELID GENUS CAMBARINCOLA — HOFFMAN 337 



sort of catch-all. Actually the jaw structure and form of the sex 

 organs is relatively stable, it is the individual and geographic variation 

 in size, shape, peristomial lobation, and such characters which lend 

 complications in the definition of specific limits. The heterogeneity 

 of "philadelphica" in the sense of previous workers is here considerably 

 abated by the extraction of a large element under the name/a//aa:, a 

 very distinctive and easily recognized form. Remaining are several 

 stumbling blocks: The disposal of some rather distinctive subspecific 

 populations now known to occur within the species, the relationship 

 of philadelphica to C. chirocephala, and the status of C. macrodonta 

 and O. meyeri. These matters are discussed more explicitly under the 

 treatments of the respective entities. 



The Philadelphica group is defined within the section by the relation- 

 ship of prostate to spermiducal gland, viz, they are essentially subequal 

 in length and collectively slightly curved and the prostate generally 

 averages from one-half to two-thirds the diameter of the gland. 

 There is no lobation (or but very little) of the gland at the entry of 

 the deferent ducts. In general the group is definable on the basis of 

 negative characters, including species not readily absorbed by the 

 other three groups. 



The male reproductive system remains remarkably similar in most 

 of the species. There are a few deviants, such as the shortened 

 prostate of meyeri and the reduced spermiducal gland of chirocephala, 

 but in general such differences are only comparative. As a rule the 

 jaws are dissimilar but equal in size except in chirocephala. An 

 exception occm's in the new species /aZ/ax, which is homognathous with 

 a 5-5 dental formula, and is placed in a separate subgTOup. In 

 most of the species the peristomium is divided into dorsal and ventral 

 halves, with the dorsal produced into low but distinct blunt projec- 

 tions or even into elongate tentacles (again injallax). Body form is 

 variable, depending to some extent on the mode of preservation, but 

 in a very general way the metasomites of chirocephala and jallax 

 tend to be appreciably greater in diameter than the prosomites, 

 imparting a strongly moniliform appearance to the outline of the 

 body. The members of the group are here considered to be relatively 

 closely related, separable largely by appeal to what I am inclined to 

 consider characters of no great phylogenetic significance, yet fairly 

 conspicuous and of the grade which has drawn the attention of most 

 previous investigators. 



Although the species themselves are not very difficult to define, 

 their disposal into groups and subgroups has not been easy to ac- 

 complish, and the present arrangement represents only an arbitrary 

 and subjective attempt. There seems to be little doubt that the 

 male sex organs provide characters of the first order, but the necessity 



