540 CRUSTACEA MALACOSTRACA. 



Parapagurus and Sympagurus S. J. Smith, deep sea. Parapagurus is 

 said to have the opening of the oviduct on the left side only. P. 

 abyssorumA. M.-E. below l,000faths. in the great oceans. It at first 

 inhabits a shell (that of the pelagic lanthina, or littoral shells are used) 

 which is subsequently absorbed by an anemone (? Epizoanthus) which 

 settles on it, and forms a covering which grows with the growth of 

 the Pagurid. Eupagurus Brandt, many species, mainly littoral. E. 

 prideauxii Leach, associated with the sea-anemone Adamsia palliata. 

 which lives on the outside of the shell inhabited by the Pagurid. 

 Nematopagurus A. M.-E and Bouv. Spiropagurus Stps. Anapagurus, 

 Hend. 



Sub-fam. 2. Pagurinae. 3rd maxillipeds approximated at their 

 bases. Pagurus Fabr. In tropical seas. Petrochirus Stps. ; Calcinus, 

 Clibanarius, Diogenes and Paguristes Dana. A form named Xylopa- 

 gurus A. M.-Edw., 100-200 faths., W. Indies, inhabits cylindrical 

 pieces of wood, the end of the abdomen modified into a posterior 

 operculum. 



Fam. 3. Cenobitidae. 1st antennae with elongated and twice bent 

 basal segments, and one of the flagella enlarged ; 2nd compressed at the 

 base. Gills foliaceous. Cenobita Latr., abdomen soft, unsymmetrical, with 

 2nd-4th appendages of left side in female, in male ; paired 6th appendage, 

 larger on left side, in both sexes. Semi-terrestrial hermit-crabs. They 

 wear Gastropod shells, and some species (the large red C. perlatus and 

 C. rugosus) are able to produce a " low chirping sound " (Borradaile). 

 The species are widely distributed in the Indo-pacific region. Birgus 

 Leach. B. latro (L.) an air-breathing Pagurid of large size sheltering in 

 holes and fissures in the ground. Carapace completely calcified ; abdomen 

 symmetrical, broad, with calcified tergal plates, its appendages as in 

 Cenobita. First trunk-legs bear very powerful chelae, the fourth small chelae. 

 The postero-lateral regions of the carapace are expanded into large pul- 

 monary chambers (Fig. 329), of which the 14 pairs of reduced gills occupy 

 a small part. The upper and outer lining of the chambers is produced 

 into ramified vascular tufts, abundantly supplied with blood-vessels, 

 the efferent vessels falling into the branchial vein before it enters the 

 pericardial sinus.* The surface is kept moist with sea-water which the 

 animals repair to the shore to renew. They feed, among other substances, 

 on the " meat " of the cocoa-nut f (they are hence known as robber 

 crabs) and carry a rich store of oil in the abdomen. Birgus latro is 

 probably to be regarded as a Pagurid whose ancestors were marine and 

 wore shells, but which has taken to a terrestrial life. 



The statement that the young of Birgus latro are hatched with the same 

 form as the parents has been shown to be incorrect. Like those of other 

 Pagurids they hatch as zoaea larvae. A female of this species was ob- 

 served by Dr. A. Willey, at Lifu, in the Loyalty Islands, at the edge of the 

 sea, with the abdomen covered with just hatched zoaeas which were being 

 washed off to start their free-swimming larval life. The zoaea larvae of 

 Coenobita have also been observed, by Borradaile.J 



* Semper, Animal Life, 3rd edition, p. 193. 



t Darwin, Naturalist's Voyage, p. 462. 



j Borradaile, L. A. On the young of the Robber-Crab (Birgus latro), 

 Willey's Zoological Results, part V, p. 585. Camb. Univ. Press, 1900, and 

 Note on the Hatching-stage of the Pagurine Land-crabs, Proc. ZooL 

 Soc., 1899, p. 937. 



