710 DR. w. T. CALMAN ON DECAPOD [June 15, 



Family GECARCiNiDiE. 



Gecabcoidea lalandii Milne-Edwards. 



G. lalandii Ortmann, Zool. Jahrb., Abth, Syst. vii. p. 738 

 (1893). 



To the synonymy given by Ortmann the following are to be 

 added : — 



Hyloiocarcinus natalis Pocock, P. Z. S., 1888, p. 561. 

 Pelocarcinus humei (Wood-Mason) Alcock, Jour. Asiatic Soc. 

 Bengal, Ixix. pt. 2, p. 449 (1900). 



Gecarchuts lagostomus (in error) Andrews, Monogr, Christmas 

 Island, p. 163 (1900). 



An examination of the Museum collection of Gecarcinidse gives 

 no reasons for dissenting from the synonymy which Ortmann has 

 established for this species. The specimen recorded under this 

 name from " S. America " by Adam White in the " List of 

 Crustacea in the British Museum," p. 32 (1847), cannot now be 

 traced, but a Museum copy of the List contains a note in the 

 handwriting of Mr. Miers, " Certainly not this species," so that no 

 confirmation is afforded of Milne-Edwards's statement that the 

 type of the species came from Brazil. 



With reference to the erroneous determination of the specimens 

 recorded in the ' Monograph of Christmas Island ' (a deter- 

 mination for which Dr. Andrews was not responsible) it is 

 desirable to point out that there is no trustworthy evidence for 

 the occurrence of Gecaj-cinus lagostoma outside the Atlantic area. 

 Milne-Edwards indeed originally described that species as 

 "rapporte de I'Australasie par MM. Quoy et Gaimard " (Hist. 

 IN"at. Crust, ii. p. 27, 1837), and Miers refers to a series in the 

 British Museum obtained in the same region during the voyage 

 of the ' Ei-ebus ' and ' Terror ' (Challenger Eep. Brachyura, p. 219 

 footnote, 1886). With regard to the latter I can obtain no 

 confirmation of the locality from the Museum registers. The 

 specimens date from a time when the records of locality were less 

 strictly kept than they are now, and it seems possible that 

 specimens arriving at the Museum without indication of locality 

 may have been assumed to come from the same i-egion as the type- 

 specimens. Miers also mentions a specimen from the Cape of 

 Good Hope, and I may add that there is another in the collection 

 labelled " Madagascar" but in neither case can the history of the 

 specimens be traced. 



Dr. Andrews has described {I. c.) the annual migration of G. 

 lalandii to the sea dm^ing the rainy season for the purpose of 

 hatching oil" the eggs. On his visit to the island in 1908, he 

 obtained specimens of a large Megalopa-larva which occurred in 

 enormous quantities in the sea shortly after the migration, and 

 also of a small crab which appeared in similar numbers at a 

 slightly later date. It seems practically certain that these larvfe 

 and young can belong to no other species than G. lalandii, and it 



