103 



right in retaining the name Brachynotus sexdentatus for the Mediterranean species and in 

 altering consequently " Heterograpsus sexdentatus" of H. Milne-Edwards from New Zealand 

 into Brachynotus edwardsii. 



Miers 1 ) in 1886 proposes to retain a subgenus Heterograpsus for the Indo-Pacific 

 species, on account of the H-shaped cervical groove distinguishing these species as a whole 

 from the single Mediterranean species; de Man 2 ), however, proves this difterence to be unstable 

 and is dispoSed rather to take the shape of the front (quadrilobate in the Mediterranean, simple 

 in the Indo-Pacific species) as the base of distinction betvveen Brachynotus and Heterograpsus. 

 But this latter criterium again turns out to be unreliable, for in the Japanese B. sanguineus 

 de Haax the front is strongly quadrilobate, at least in adult specimens. 



As to Hemigrapsus, the only difference pointed out by Dana is the more or less distinct 

 notching of the inner margin of the external maxillipeds, and this indeed seems to be of 

 doubtful value. Stimpson :i ) referred Dana's two new species of Hemigrapsus to the genus 

 Cyrtograpsus Dana, but A. Milne-Edwards 4 ), Kingsley ~') and Haswell 6 ) all agree in declaring 

 Hemigrapsus absolutely identical with Heterograpsus. For some unknown reason Miss Rathbun 

 in several publications persists in using Dana's name Hemigrapsus. 



The sharply-defined and pointed antero-lateral teeth of the carapace and the non-auriculate 

 shape of the merus of the external maxillipeds distinguish this genus from Pseudograpsus. 



It is remarkable, that this Pacific genus has one solitary species in the Mediterranean, 

 whereas it is wholly absent in the Atlantic. It is represented at the coasts of Japan and China, 

 of California and Chile, in Indonesia, but chiefly in Australian and New Zealandian waters. The 

 Malay Archipelago affords only one single species [B. har pa x Hilgendorf), for another species, 

 as has been remarked a few pages before (under the head of Pseudograpsus lauiger), viz. 

 Heterograpsus elongatus H. Milne-Edwards, recorded by Nobili. 7 ) from Borneo, should in my 

 opinion be- included in Pseudograpsus (see p. 101 — 102). Not a single species, as far as I 

 know, has been found in the Indian Ocean, but B. harpax is again found in the Red Sea. 



The rather numerous species of Brachynohis may be divided into two distinct groups : 

 one, very small, in which three minute teeth, behind the external orbital angle, are observed 

 and another, much larger, with only two very large and usually depressed teeth behind this 

 angle. H. Milne-Edwards' attempts to subdivide the species of the latter group on account 

 of the presence or absence of longitudinal crests on the palm of the chela have remained 

 unsuccessful. 



Though no species of this genus were collected by the "Siboga", I have taken this 

 occasion to review shortly the various species, for the collection of the Leiden Museum is 

 rather rich in this regard. I believe the best discrimination of the species is to be found in the 



1) Rep. "Challenger", Brachyura, 1886, p. 264. 



2) Zool. Jahvb., Syst., Bd 9, 1895, p. 123. 



3) Sir.hhson. Inst., Miscell. Coll., v. 49, 1907, p. 125. 



4) Nouv. Arch. Mus. Paris, t. 4, 186S, p. 177. 



5) Pioc. Ac. Nat. Sc. Vhiladelphia, 1880, p. 207 — 209. 



6) Cat. Austval. Crnst., 1882, p. 100 — 101. 



7) Boll. Mus. Torino, t. 18, n° 447, 1903, p. 25. 



