Vol. IX, No. 6.] Crustacea Decapoda of the L. of Tiberias. 251 
[N.S.] 
KEY TO THE CRABS OF THE Poltamon potamios GROUP. 
I. Epigastric crests only a little in advance of post- 
orbitals and parallel to them; post-orbitals 
pted 
or angulate at anterior end of cervical groove P. potamios. 
II. Epigastric crests usually well in advance of post- 
s 
tals sinuous, convex forwards or slanti dis- 
tinetly interr i aa ane get at anterior 
end of cervical groo .. P. fluviatile, s.l. 
Races of P. fluviatile. 
A. Length of carapace nearly seven-eighths its 
a nt oben of last leg less than twice 
bro fluviatile. 
B. Genii of ¢ crea usually less = five-sixths 
th bre adth; p propodus od reg usually at 
t twice as ne as bro 
L_ Carapne setos ; A .. setiger. 
2. Carapace not ai se 
a. Middle portion of cervical groove on — 
obsolete, anterior part not v 
astric crests 
less in advance of peoe Sehteal ate .. gedrosianum. 
So far as we are aye to judge from the descriptions given 
by Miss Rathbun ‘and Dr. Pesta *, we are doubtful whether P. 
mens in the collection of the Indian Museum and oe them in 
an appendix. They may be summarised as follows:~ 
1 Mem, Mus. Hist. Nat., Pars (4), VI, p. 258. ae 3, pl. ix, fig. 2. 
; o~ Ann. k. k. naturhist. Hof mus., Vienna, XXVII, p. 27. text-fig.12. 
8 Cat. Ind. Decap., Crust. I, fase. 2, Potamonidae, pp. 21-23, figs. 
1, 37. 1910, 
