1905. ] ORTMANN — AFFINITIES OF CAMBARUS. 109 
and a rather long or moderate acumen. ‘The carapace is of normal 
shape, oval and depressed ; the areola uniformly rather wide, and 
there is no tendency to become narrow. There ‘are, however, 
some differences in length: generally, the areola is about half as 
long as the anterior section of the carapace (incl. rostrum); but in 
certain species (evichsoni and forceps) it is slightly, and in one 
species (sfzzosus) decidedly shorter, and in two others (swsticus 
and medius) it is decidedly longer. The chelz in this section“are 
also rather uniform, but not very primitive: they are more or less 
broad and ovate. ‘The fingers (in old males) generally are gaping 
at the base, and in contact distally, and the movable finger pos- 
sesses a peculiar S-shaped curve. ‘The immovable finger is generally 
‘not bearded at the base (a slight indication of a beard is seen in: 
C. propinguus, obscurus, neglectus). In C. forceps, the fingers are 
unusually and widely gaping, upto the tips. In C. medius the chelee 
are unusually broadly ovate, and the movable finger has no S-curve. 
The annulus of the female is flat, with a median depression and 
raised margins. Very often the anterior margin is elevated into 
tubercles, and in C. hy/as the posterior margin is very prominent, 
which is rather unusual in this section, and ought to be confirmed 
by additional investigations. 
This section contains ten species, which may be divided into two 
groups. c 
1. Group: ( propinquus). 
Tips of sexual organs comparatively short, reaching only to the 
third rarely (in erichsonianus) to the second peretopods, without or 
with (obscurus) a shoulder on the anterior margin. Outer tip regu- 
larly tapering from base to end. 
2. Group: (rusticus). 
Tips of sexual organs long, reaching rarely only to the second, gen- 
erally to the first peretopods, mostly with a shoulder on the anterior 
margin. Outer tip not regularly tapering, but thin (setiform) from 
base to end. 
C. erichsonianus forms a transition between the two groups: the 
sexual organs are rather long, but they lack a shoulder, and in shape 
they resemble those of C. propinquus. 
3. Section: C. virths. 
Sexual organs generally quite long (rarely rather stout), reaching 
about to the second peretopods, deeply split at the tips, lips slender 
