92 ORTMANN— AFFINITIES OF CAMBARUS. 



[April 



the fourth, and he apparently believes, that it is connected genet- 

 ically with the latter. The geographical distribution, however, is 

 opposed to this assumption, and a closer study has led me to think 

 that there is no such affinity between these two groups, and that the 

 fifth is more closely allied to the first and second. (Compare Ort- 

 mann, I. c, 1902, p. 283.) 



2. Faxon believes (/. c. , 1885, p. 19) that the first group con- 

 tains the most primitive forms. This is not probable when we con- 

 sider the very highly specialized character of most of the species. 

 Indeed, there are rather primitive forms among them, but they are 

 clearly not as primitive as certain species of the second group (Ort- 

 mann, 1903, p. 283), and further, the main range of the first group 

 occupies a territory that is, geologically, comparatively young, 

 namely, the lowlands of the southern states (Mississippi, Alabama, 

 Georgia, Florida), of which we know that they became land by 

 degrees during the Tertiary period, the more southern parts in very 

 recent times. It is not very likely that this recent land is occupied 

 by an ancient group of animals. 



3. I strongly object to placing Cambarus pellucidus, the blind 

 cave-species of Kentucky and Indiana, with the first group, where 

 it stands entirely isolated, morphologically as well as geographically. 

 If we place this species at the beginning of the fourth group, it 

 comes into an assemblage, from which it is not so strongly differ- 

 ent. It will always remain a remarkable, and, as Faxon believes, 

 a primitive type, but it is not the most primitive type of the genus 

 in all respects. In the shape of the male organs it certainly points 

 rather to the fourth group than to the first. 



4. Faxon places C. blandingi at the head of the genus: this is 

 apparently due to the desire to let the type-species of the genus 

 stand first. This, however, may convey the wrong impression, 

 that C. blandingi is the lowest (or else the highest) form of the 

 whole genus. But I do not think that it is either, and regard it as 

 a highly specialized (but not the most highly specialized) form of 

 a branch of the genus that is rather ancient. The distribution of 

 C. blandingi has all the characters of a comparatively modern 

 encroachment upon foreign territory. 



5. I believe that the second group of Faxon contains the most 

 primitive types of the genus. But this is to be understood "cum 

 grano salis." There are, in this group also some very highly 



