118 ORTMANN — AFFINITIES OF CAMBARUS. [April 13, 
nulus of the female is, corresponding to the uniformity of the male 
organs, also very uniform, and is characterized by its posterior ele- 
vation. Aside from the length and width of the areola, the shape 
of the chelee, the presence or absence of marginal spines of the 
rostrum, and the shape of the carapace serve to distinguish the more 
primitive forms from the more highly developed, and furnish a 
division of the subgenus into sections as follows : 
1. Section: C. hamulatus. 
Carapace subcylindrical. Rostrum with or without marginal 
spines. Chele long, subcylindrical. Areoia rather long. Eyes 
rudimentary. 
Only two species, C. hamulatus and setosus, belong here, both 
blind cave-forms. They do not seem to be closely related to one 
another, since they differ in very important characters. The sub- 
cylindrical shape of the chelz, however, indicates, that both are 
rather primitive, and have become separated from the primitive 
stock of this subgenus very early, and probably independently. 
The shape of the carapace, the long areola, and the rudimentary 
eyes are very likely due to parallel development, brought about by 
the similar conditions under which these species are found. (See 
Faxon, Pr. U. S. Mus., v. 12, 1890, p. 628). 
2. Section : C. extraneus. 
Carapace more or less ovate, depressed, with lateral spines behind 
cervical groove. Chele not very elongated, depressed, and rather 
broad, but a little more elongated than in the following sections. 
Areola more or less wide, of medium length, about half as long as 
anterior section of carapace, sometimes slightly shorter, rarely, in C. 
cornutus, the areola ts rather long. Eyes well developed. 
Two of the species belonging here (C. extraneus and jordant) 
are typical, and are unquestionably the most primitive forms of the 
subgenus, as is shown by the shape of the carapace, the rostrum, 
and chelz, at least as compared with the following sections. The 
third species, C. cornutus, stands by itself, and is a rather aberrant 
form, peculiar on account of its antennz, which have a large, com- 
pressed flagellum, ciliated on inner margin. Also the spines of the . 
rostrum (upturned) are peculiar. In the long areola, it is rather 
advanced. It seems to be a peculiar local form, developed out of 
the primitive stock now represented by C. extraneus and jordant, 
and we may safely leave it with this section, since the only alter- 
native would be to create for it a separate section. 
