116 QRTMANN — AFFINITIES OF CAMBARUS. [April i 3 , 



the changes of the drainage systems in the southern Appalachians, 

 see: Simpson, Science, 12, 1890, p. 133, and chiefly Adams, 

 Americ. Natural., 35, 1901, p. 844 ff. ; where on p. 849 three 

 species of Cambarus are mentioned (C. spinosus, extraneus, and 

 erichsonianus) that belong into this category). The species C. 

 neglectus, hylas, and medius belong to the southwestern and western 

 edge of the range of rusticus, and are found in Missouri, Arkansas, 

 Texas, Kansas, and Iowa. Thus it is evident, that the six species 

 morphologically allied with C. rusticus in the same group, express 

 this relation also in their distribution, being apparently locally 

 modified forms of the rusticus-type, and being naturally found 

 just where we ought to expect them, namely at the edge of the 

 range of this rusticus-type. 



C. erichsonianus seems to be abnormal : morphologically we have 

 placed it with C. propinquus, but its range is far remote from it in 

 eastern Tennessee and central Alabama (in both the Tennessee 

 and Alabama river drainages). But, as we have seen above, its 

 position is a little uncertain, it resembling C. rusticus and its allies 

 to a degree, and the distribution suggests the same : it clearly 

 agrees better in this respect with C. forceps and spinosus, and it 

 would thus become another local form of the rusticus-type. Fur- 

 ther investigations on this question should be made. 



The third section, that of C. virilis, has been divided into three 

 groups. The virilis-group agrees somewhat with the rusticus-group 

 in its range, belonging to the central basin, only being a little 

 more western, and considerably more northern : it is hardly found 

 in the drainage of the Ohio, but it is very abundant in that of the 

 Mississippi and Missouri, and crosses over not only into the lake 

 drainage, but also into that of Hudson Bay (Winnipeg Lake). 

 The typical species of the group {virilis) occupies almost all of 

 this range, while four other species associated with it (nieeki, longi- 

 digitus, nais, f>ilosus) apparently are local forms of it, being found 

 at or near the southwestern extremity of the range of C. virilis 

 in Arkansas and Kansas. C. i/nmunis is a peculiar type of the 

 virilis-group, and its range coincides with the southern part of the 

 range of C. virilis (Kansas, Missouri, Iowa, Illinois, Indiana, 

 Ohio) : this is interesting in so far as this occupation of the same 

 territory by two closely allied species is rendered possible as it 

 seems in this case, by the different habits : as far as we know, C. 



