96 ORTMANN — AFFINITIES OF CAMBARUS. [April 13, 
[It is very remarkable, that burrowing crayfishes of the southern 
hemisphere (Parastacus defossus Fax. from southern Brazil is at 
hand) resemble the North American burrowing species in a remark- 
able degree externally, chiefly so in the shape of carapace, rostrum, 
chelz, length of abdomen, etc. | 
The Che/e are very variable in shape: they are fully developed 
only in old males, but generally quite characteristic for the species. 
One and the same type is often common to large groups of species, 
and thus they are often a good help in the investigation of the 
natural affinities. But in other cases a similar form of chelz is 
found in different groups which is most striking again in the bur- 
rowing species. 
Among the more primitive species the shape of the chelze seems 
to be more or less subcylindrical, and rather elongated. This 
shape is found in Faxon’s first, second, third, and fifth groups, but 
only in the first, second and fifth it is frequent. Removing C. 
pellucidus to the fourth group, also in the latter this type of chelz 
is represented. In part of the second group, and in the third and 
fourth, a more or less ovate, broad, and depressed chela becomes 
common, but there is not much uniformity in detail, each group 
generally developing its own type. 
The above are the more important characters. We see that all 
of them must be dealt with cautiously, if they are to be used for 
the investigation of affinities of species. Indeed, in many cases, 
they support the conclusions arrived at by the examination of the 
the sexual organs, but very frequently similarities of the above 
characters are due to convergency. The same is true of all other 
characters, such as armature of carapace, chelz, shape of epistoma, 
antennal scales, of abdomen, telson, etc. 
SUBGENERA OF CAMBARUS, ACCORDING TO THE CHIEF TYPES OF THE 
1 SEXUAL ORGANS OF MALE. 
There are three chief types of the male sexual organs (first pair 
of abdominal appendages), the last of which is easily divided into 
two subtypes. According to these, I should like to distinguish 
four subgenera, as follows : 
1. Subgenus: CAMBARUS (sens. strict. ). 
Sexual organs of male s¢owf, more or less straight, and compara- 
tively short, ¢rwncated or blunt at the tip, the outer part ending in 1-3 
