331 



LiMNORIA IN THE PACIFIC ISLANDS 



Limnoria lignoriim occurs in considerable nimibers in Pearl Harbor and, with 

 Limnoria andrewsi, in Honolulu Harbor. A light and scattered attack by L. lignonim 

 has occurred in test blocks from Nawiliwili Bay, Island of Kauai. 



The specimens from Hawaii are smaller than is usual for this species in our colder 

 waters, averaging somewhat under 2.5 mm. in length. The length usually given for 

 L. lignorum is 3 mm. In San Francisco Bay the average length of adults of this species 

 is 3.5 mm. 



Limnoria andrncsi (fig. 135) may be distinguislied from L, lignonim, as from 

 the five other known species of Limnoria, by the relative shortness of the peduncle of 

 the uropods; this in L. andrewsi is equal in length to or shorter than the outer ramus 

 or exopodite of the uropods, while in all of the other species the peduncle exceeds the 

 exopodite in length. 



This species occurs in the test blocks from .Samoa in approximately the same 

 numbers as Clielura insulac (vide infra). The result of the combined action of the 

 two is shown in figure 136, /. Limnoria andrewsi also occurs with L. lignorum in 

 Honolulu Harbor, where it greatly outnumbers the latter species, and at Nawiliwili, 

 where both occur in limited numbers. 



It is remarkable that, while Limnoria andrewsi is the dominant species in the 

 test blocks from Honolulu Harbor, in the blocks from Pearl Harbor, cjnly a few miles 

 distant, L. lignorum predominates to such an extent that if L. andreivsi occurs at all 

 its presence has been o\erlooked. No crustacean borers have been found in the limited 

 number of blocks recei\ed from the Philippine Islands. 



Genus Sphaeroma 

 The crustacean borers of the genus Sphaeroma are much larger and stouter 

 organisms than Limnoria, but with the same general structure. On account of their 



Fig. 135. Limnoria andrewsi from Tutuila. 1, dorsal: 2, lateral and ^, ventral views of female 

 carrying advanced embryos in brood pouch. X 17. 



habit of rolling up into a ball when disturbed the\- are somewhat commonly known 

 as "pill bug borers." In general they are not of much economic importance, but one 

 or two species, particularly Sphaeroma destructor of the Florida Coast, are reported 

 as occasioning considerable damage. Only one species occurs on the Pacific Coast of 

 North America. 



