Hapalocarcinus, the Gall-forming Crab, etc. 69 



SUMMARY. 



Hapalocarcinus. 



(1) The stages in the formation of galls in colonies of Pocillopora and 



Seriatopora are here fully described. 



(2) The male, here described for the first time, is found in open galls with 



females which have just reached maturity. It is rather smaller 

 than the youngest female here described. 



(3) The females vary in size, from very small individuals with narrow 



abdomen without appendages, gonads and generative apertures 

 not having been yet formed, to large forms with hypertrophied 

 abdomens forming brood pouches laden with developing eggs. 

 The galls correspond in development to their inhabitants. 



(4) The peculiarities of the buccal appendages and the reduction of the 



armature of the stomach are explained by supposing that the 

 crabs live on the nannoplankton drawn into the galls with the 

 respiratory current. This is supported by the fact that the 

 stomach is always apparently empty, closer examination some- 

 times showing very minute organisms. 

 Cryptochirus. 



(5) In Cryptochirus coralliodytes the male does sometimes form shallow 



pits and does not inhabit the same pit as the female. 



(6) The sexual dimorphism in this species is much less marked than in 



C, dimorphus. 



(7) Buccal appendages and stomach exhibit the modifications found in 



Hapalocarcinus and a similar method of feeding is probably 

 employed. 



BIBLIOGRAPHY. 



1. BORRADAILE, L. A. Fauna and geography of the Maldive and Laccadive Archipelagoes. 



Vol. i, Marine Crustaceans, vol. in, Xanthidse and some other crabs, [p. 271 for Hap- 

 alocarcinidse.] 



2. CALMAN, W. T. 1899. On a collection of Brachyura from Torres Straits. Trans. Linn. Soc., 



Zoology, 2d ser., vol. 8, pt. i, p. 43. 



3. HELLER, CAMILL. 1861. Beitr. 2, Cruataceen-Fauna des rothen Meeres. S. B. Akad. Wien. 



43 (1), p. 366, pi. ii, fig. 33-39. 



4. HENDERSON, J. R. 1906. On a new species of coral infesting crab taken by the R. I. M. S. In- 



vestigator at the Andaman Islands. Ann. Mag. Nat. Hist., ser. 7, vol. 18, pp. 211-219, 

 pi. vin. 



5. SEMPER, KARL GOTTFRIED. 1881. Natural conditions of existence as they affect animal life. 



The International Scientific Series, London, (pp. 216-224 for Hapalocarcinus and 

 Cryptochirus) . 



6. VERRILL, A. E. 1867. Remarkable instances of crustacean parasitism. Amer. Jour. Sci. (2) 



vol. 44, p. 126. 



7. . 1869. On the parasitic habits of Crustacea. Amer. Nat., vol. in, p. 239. 



8. . 1870. Synopsis of the Polyps and Corals of the North Pacific Exploring Ex- 

 pedition. Proc. Essex Inst., vol. vi (1868), p. 91. 



