338 



Chelura terebrans 



This species is at present known from the Atlantic coasts of North America 

 and Europe, from the Cape of Good Hope, and from New Zealand (see Caiman, 

 1921). It will be briefly mentioned here for comparison with the onh* other known 

 member of the genus, C. insulae, and in ^•iew of the omnipresent possibility of its 

 introduction on the Pacific Coast. 



The organism (fig. 140) is readily identified by certain rather marked character- 

 istics, chief among which is the presence of a prominent, stout cur\'ed spine project- 

 ing from the posterior margin of the third abdominal segment on the dorsal side of 

 the body. The body at the segmental joints, the antennae and the legs are clad with 

 numerous long hairs. The terminal segments of the last pair of abdominal appendages 

 in the male are highly modified as two long, stout, smooth club-shaped structures 

 nearly half as long as the body. 



Chelura works with Limnoria in marine structures, and has rarely, if ever, been 

 reported as occurring in the absence of the latter organism; hence its presence may 

 often be overlooked under such circumstances. 



Chelur.a insulae Calman 



This species (fig. 141) was described by Caiman (1910) from Christmas Island in 

 the Indian Ocean. It may readily be distinguished from Chelura terebrans by the longer 

 antennae and antennules, the enormously developed anterior gnathopods, and absence 

 of the prominent spine on the third abdominal segment which characterizes C. terebrans. 

 In C. insulae the hind margin of the third abdominal segment carries three short 

 tubercles. The brush of hairs on the third uropods of the male is a further peculiarity 

 of this species. 



Chelura insulae occurs in great numbers in the blocks from Samoa, following up 

 Limnoria and enlarging the burrows of the latter for its own occupancy. The organism 

 apparently bores for food as well as shelter, as the passages it makes (fig. 135, 3) are 

 considerably larger than would be required for the latter purpose alone. The appear- 

 ance of wood that has been attacked by both Chelura and Limnoria (cf. fig. 135, 1) is 

 characteristically different from that which has been attacked by Limnoria alone. 



Chelura insulae also occurs, though less numerously, in the blocks from Honolulu 

 Harbor. 



LITERATURE CITED 

 Andrews, A. 



1875. Limnoria terebrans attacking telegraph cable. 

 Quart. Jour. Micros. Sci., 15, 332. 

 Barrows, A. L. 



1917. An unusual extension of the shipworm in San Francisco Bay, California. 

 Univ. Calif. Publ. Zool., 18, 27-43. 



1919. The occurrence of a rock-boring isopod along the shore of San Francisco 

 Bay, California. Univ. Calif. Publ. Zool., 19, 299-316, pis. 15-17. 

 Bartsch, p. 



1916. A new Teredo from the west coast of America. Nautilus, 30, 47-48. 



1921. A new classification of the shipworms and descriptions of some new wood- 



boring mollusks. Proc. Biol. Soc. Washington, 34, 25-32. 



1922. A monograph of the American shipworms. Bull. U. S. National Museum, 



122, 51 pp., 37 pis., 1 fig. in text. 



1923. Additions to our knowledge of shipworms. Proc. Biol. Soc. Washington, 



36, 95-102. 



