128 ORTMAXX — AFFINITIES OF CAMBARUS. 



[April 13. 



dent in the following cases, where groups of species occupy a cer- 

 tain range, but represent each other in the different parts of this 

 range : ( 1 ) in the spicalifer-group of the subgenus Cambarus : spic- 

 ulifer in northern and central Georgia, versutus in central and 

 southern Alabama, and in northwestern Florida, pubescens in eastern 

 Georgia, angustatus in southeastern Georgia. (2) In the clarki- 

 group : clarki, parallel to the Gulf coast from Texas to Florida, 

 troglodytes in corresponding localities in Georgia and South Caro- 

 lina. (3) Limosus-section of Faxonias : indianensis in southwestern 

 Indiana, sloanei in southeastern Indiana and Kentucky. (4) Pro- 

 pinquus-group : propinquus has a western and northern distribution ; 

 it is represented in western Pennsylvania by obscurus. (Between 

 both possibly is C. prppinquus sanborni, occupying an intermediate 

 range.) (5) Rusticus-group : spinosus is southern and eastern 

 (North and South Carolina, northern Georgia, northern Alabama 

 and eastern Tennessee), while putnami is more northern (Ken- 

 tucky). (6) In the palmeri-group the different species occupy dif- 

 ferent parts of a range that includes Mississippi, western Tennessee, 

 Arkansas, Indian Territory and northeastern Texas. 



Groups of allied species are oj ten formed by a typical species, which 

 shows a wide range, while the allied species form a fringe on the edge 

 of this range thus representing local forms. This is shown beauti- 

 fully in the following natural groups : (1) Rusticus-group: the typ- 

 ical form is rusticus, the local forms at the edge of its range are : 

 forceps (southeast), neglectus (west and southwest), spinosus and 

 putnami (southeast), hylas (south), medius (south); probably also 

 erichsonian us (southeast). (2) Virilis-group : the typical form is 

 virilis, the local forms are : mceki, longidigitus, nais, pilosus, all in 

 the southwest. (3) Barto?ii-section: bartoni is the typical form, the 

 local forms of it are : acuminatus (southeast), latimanus (south and 

 southwest); in this section also a mountain form has developed 

 within the range (longulus), and varieties are found in the southern 

 section of the range, as well as at its northwestern edge. (4) C. mon- 

 ongalensis is a local form developed at the northwestern edge of the 

 range of C. carolinus. (5) In the diogenes-section, at least one 

 species, C. uhleri, seems to be a local form of the widely distributed 

 C. diogenes, developed at the eastern extremity of its range. 



More or less closely allied species, occupying the same or nearly the 

 same territory, generally possess different habits. In most of the 



