128 ZOOLOGISCHE MEDEDEELINGEN — DEEL IIT. 


overlooked '); yet I hope such cases will not seriously interfere with 
its possible value. 
Further I have tried to give a key to the Indo-Pacific species of the 
_genera dealt with. As to the American species of Sesarma we possess a 
valuable, though rather concise, key, prepared by Miss Rathbun (Proc. 
Biol. Soc. Washington, v. 11, 1897, p. 89—92) and, though the number 
of species of course has increased during the last twenty years, her 
synopsis certainly has retained its value. Now it is a remarkable fact, 
that, with the only exception of a key to the subgenus Parasesarma by 
de Man (see Zool. Jahrb. Syst., Bd. 9, 1895, p. 181—182), never any 
attempt has been made to introduce the beginning student into the deter- 
mination of Indo-Pacific Sesarma-species, be it only in a preliminary way, 
by means of a synoptical key *). I have tried to fill up this gap, but in 
how far my attempts are successful may only be decided by practice. 
Determinations made by using this key should of course always be veri- 
fied by perusing the literature and the most extensive description of the 
particular species, and it is for this reason, that, for the sake of con- 
venience, I ranged the species merely alphabetically, without 
regarding the subgenus (though this is always mentioned), in order 
to save time to the reader. 
Where it appeared necessary I have added a few remarks of my own 
in order to indicate the affinities and points of difference between closely 
allied species. 

I. Synopsis of all the species of Sesarma, Metasesarma, 
Sarmatium and Clistocoeloma. 
* A. Sesarma Say 1817. 
1. Sesarma (Sesarma s.s.) aequatorialis Ortmann. 
1894. Sesarma aequatorialis Ortmann. Zool. Jahrb. Syst., Bd. 7 p., 722, 
pl. 23 f. 14 — Ecuador. 
1897. Sesarma (Sesarma) aequatorialis Rathbun. Proe. Biol. Soc. Was- 
hington, vy. 11 p. 112 — no new locality. 
1901. Sesarma (Sesarma) aequatorialis Nobili. Boll. Mus. Torino, t. 16 
n°. 415 p. 44 — Esmeraldas. 
1) The mere mentioning of names, without adding any description or new record, of Kings- 
ley in his Revision of the Grapsidae (Proc. Ac. Nat, Sc. Philadelphia, 1880) has not been in- 
cluded here. 
2) The well known memoir of Alcock (Journ. As. Soc. Bengal, v. 69 prt. 2,1900) deals 
only with Indian species, 
