wae ORTMANN— AFFINITIES OF CAMBARUS. 115 
home, while C. “mosus 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. “mosus 
reached its present habitat. 
The section of C. propinguus 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 propinguus- 
group, C. propinguus, 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. propinguus, 
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. 
propinguus, namely in the upper Ohio drainage in western Pennsyl- 
vania and western New York (See Ortmann, Ann. Carnegie Mus., 
V. 3, 1905, p. 387-406), and seems to be the representative form 
of C. propinguus, 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. propinguus 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 ot 
these two species, rusticus and propinguus, in Ohio, Indiana, Illi- 
nois, Michigan, and Wisconsin will certainly be very interesting. ) 
Associated with C. rus¢icus 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 (sfzmosus) has crossed over into 
the Gulf and Atlantic drainages in northern Georgia, South and 
North Carolina. (This is an additional case throwing light upon 
