98 ORTMANN — AFFINITIES OF CAMBARUS. [April 13, 
ending, a character that possibly points to the condition seen in 
the genus Pofamodius ; for the rest, the terminal teeth are quite 
variable, but always very characteristic for the species. 
It is advisable to distinguish groups within this subgenus, not 
only with reference to the sexual organs, but also with reference 
to the hooks of the male, for the presence of one or two pairs of 
hooks seems to constitute, as already Faxon recognized, important 
differences, the presence of two pairs, on third and fourth pereio- 
pods, being evidently a more advanced stage. Using in addition 
some other differences of the areola and the chelze, we obtain the 
following three sections. 
I, Section, -C..disuer. 
Sexual organs of male with one to two teeth at the tip of the outer 
part. Male with hooks on third peretopods. Areola wide or nar- 
row, but never obliterated, about half as long as the anterior section 
of the carapace (incl. rostrum), or shorter. Chele elongated and 
subcylindrical, 
2. Section: C. gracils. 
Sexual organs of male with one to two teeth at the tip of the outer 
part. Male with hooks on third peretopods. Areola obliterated in 
the middle, considerably longer than half of the anterior section of 
the carapace. Chele short, broad, ovate. 
3. Section: C. blandingt. 
Sexual organs of male with one to three teeth at the tip of the outer 
part. Male with hooks on third and fourth peretopods.  Areola 
wide or narrow, rarely obliterated tn the middle, shorter or longer. 
Chele generally elongated, narrow, and subcylindrical. 
The most primitive sexual organs are found in species of the first 
section, where there is only one tooth at the end of the outer part. 
Similar sexual organs are found in the second (C. advena) and in 
the third section (C. evermannz): in the latter cases, however, I 
think we have to deal with parallelism, the single tooth in both 
cases being due possibly to reduction. Since these two species are 
very rare and poorly known, and since C. evermanni belongs to a 
group that offers other difficulties, further investigations are needed. 
A closer examination may reveal the fact, that the sexual organs 
of the dgueti-group are more sharply distinguished from those of 
C. advena and evermanni. ‘Through the courtesy of Professor E. 
Bouvier of Paris, I have received two cotypes (male and female) 
