on 17 of the 29 control panels and on 18 of the same niniiber of test 

 panels. Tub\ilaj:ia vas the only form identified. 



"b. Bryozoa (encrusting and filamentous ). Six colonies 

 Df an encrusting Bryozoa occurred on the last panel in the test series. 

 Fllamentoiis Bryozoa occurred more or less ahundantly on k of the 29 

 control panels and on 9 of the same number of test pajiels . Bufiula sp . 

 was the only form identified. Filamentous Bryozoa occurred more or less 

 abundantly on k of the 29 control panels and on 9 of the same number 

 of test panels . Bugula sp. was the only form identified. 



c. Annelida (marine worms ). Serpulid ( Serpula ) tubes occurred, 

 often in great abundance, on 25 of the 29 control panels and on 26 of 



the same number of test panels, the maximum length on any panel being 



20 mm. Eleven of the control panels were from 25^ to 100?^ covered, eind 7 



of the test panels were from 50^ to 100^ covered. 



d. Arthropoda (crustaceajis ). Balanus (barnacles) occurred 

 in rather scanty numbers on Ik of the 29 control panels and on 10 of the 

 same number of test, panels, the maximum number being only 5OO on any 



One panel. A maTlTmim diameter of 6 mm was recorded on the control panels 

 and 12 mm on 2 test panels after 5 and h months' submergence, respectively. 



e. Chordata (tunicates ). From 10 to 12 colonies of tuni- 

 cates occurred on 2 test panels. 



Akl . 05 Sinrmmvy and Conclusions 



1. Installation . A test board of the panel type, installed 

 at the II. S. Maval Operating Base at the Midway Islands in the centred 

 Pacific t)cean on July 21, 19kk, is still being operated. The results 

 of this test have been summarized to the end of 19^7- 



2. Test Eesults . 



a. Borers . Teredinidae were active each year, and the 

 breeding season was continuous. The attack rated moderate each year 

 except 19^6, when it attained a peak rating of heavy. Limnoria were 

 extremely active throughout the period of the test. .Except during 

 19^7^ when the test board was operated only briefly, the attack was 

 extremely" heavy throughout the year, and panels were almost completely 

 destroyed in 8 months. The panels continued to be partially destroyed 

 even after the period of submergence had been reduced to k months. 

 This is the most severe Limnoria attack that has been recorded from 

 any locality. No Fholadidae were recorded from this location. 



221 



