No. XL— MARINE BKACHYURA. 



By Mary J. Rathbtjn, Assistant Curator, Division of Marine Invertebrates, 

 United States National Museum, Washington, U.S.A. 



(Plates 15—20 and Text-Figures 1, 2.) 

 (Communicated by Prof. J. Stanley Gardiner, M.A., F.R.S., F.L.S.) 



Read 2nd February, 1911. 



The collection of crabs is a large one, comprising 245 species and subspecies ; of these, 

 33 species and 3 subspecies are new to science, and for 3 of the species new genera are 

 constructed. 



The majority of the previously described species are entered in the works by Alcock, 

 Laurie or Borradaile on the Brachyura of India, Ceylon and the Maldives, or form part 

 of the Indo-Pacific fauna. Among the exceptions are three species from the Seychelles 

 which have been recorded hitherto only from the Red Sea, or Persian Gulf, or both, viz. : 

 Atergatopsis signata, Actumnus bonnieri and Eumedonus granulosus. Another Red Sea 

 form, Actumnus globulus, was taken by the " Sealark " at the Chagos Archipelago. 



The results of the expedition show no connection with the West African fauna. The 

 genus Callinectes, it is true, is found for the first time in the Indian Ocean. This genus 

 reaches its greatest abundance both as to species and individuals, in temperate and 

 tropical America, and is fairly abundant on the west coast of Africa. The Indian species, 

 however, is similar to, if not identical with, that lately recorded from the " Albatross " 

 collection in the South Pacific. 



Most numerous among the "Sealark" crabs are the small oval Xanthids, as Aetata, 

 Carpilodes, Pilumnus, etc. To the same family belongs a new and widely divergent type 

 with a stridulating mechanism, which has been named Gardinena in honour of the leader 

 of the expedition. A different arrangement for producing sound is presented by a new 

 species of Marietta; it is the first occurrence of the sort noted among the Palicidaj. There 

 is an entire absence of Pinnotheridse and, save for one species of Typhlocarcinops, of those 

 hemispherical forms of the Gonoplacidte which were so abundant in Dr Mortensen's 

 collection in the Gulf of Siam'". 



* K. D. Vidensk. Selsk. Skr., 7 R., n.— m., Afd. v. 4, 1910, pp. 303—368, text-tigs. 1-44, pis. 1-2, 1 map. 

 SECOND SERIES— ZOOLOGY, VOL. XIV. 25 



