I9 o S .] ORTMANN — AFFINITIES OF CAMBARUS. 115 



home, while C. tiniosus apparently is an early emigrant that has 

 crossed over into the Atlantic drainage, and has been entirely 

 cut off from the connection with the original stock. At present, 

 I am not prepared to say which was the way by which C. limosus 

 reached its present habitat. 



The section of C. propinquus contains quite a number of species : 

 studying their distribution, we see that the distributional areas of 

 the two groups into which this section is divided correspond to the 

 main ranges of two species, while the other species seem to be 

 rather local forms of these. The typical form of the propinquus- 

 group, C. propinquus, occupies a continuous range that belongs in 

 part to the Mississippi drainage (Iowa, Illinois, Minnesota), in an- 

 other part to the Ohio drainage (in Indiana), and for the rest to 

 the Lakes and St. Lawrence drainage (in Michigan, Ohio, Penn- 

 sylvania, New York and Canada). Compared with C. rusticus, 

 this range is more northern and northeastern, and it is remarkable, 

 that there is hardly a locality known for the typical C. propinquus, 

 that lies south of the Terminal Moraine of the Wisconsin ice 

 sheet. C. obscurus is found at the eastern edge of the range of C. 

 propinquus, namely in the upper Ohio drainage in western Pennsyl- 

 vania and western New York (See Ortmann, Ann. Carnegie A/us., 

 v. 3, 1905, p. 387-406), and seems to be the representative form 

 of C. propinquus, in this region. 



C. rusticus, the typical species of the other group of this section, 

 has a wide range over the central basin, from Ohio, Indiana, and 

 Kentucky to Iowa, Missouri, and Tennessee. With reference to 

 C. propinquus it is more southern and western, although it extends, 

 in Ohio, far northward, and is found in the lake drainage in Michi- 

 gan and Wisconsin. (The investigation of the distribution 01 

 these two species, rusticus and propinquus, in Ohio, Indiana, Illi- 

 nois, Michigan, and Wisconsin will certainly be very interesting.) 

 Associated with C. rusticus in the same group are six other species : 

 all of these are rather local, and all are found at or near the edge 

 of the range of C. rusticus. C. forceps, spinosus, and putnami are 

 found at the southeastern edge, namely in the Cumberland and 

 Tennessee river drainages in Kentucky, Tennessee, and northern 

 Alabama. One of these species (spinosus) has crossed over into 

 the Gulf and Atlantic drainages in northern Georgia, South and 

 North Carolina. (This is an additional case throwing light upon 



