of the panels did not solve the problem, as It was soon discovered that the 

 more wood present the greater Taecame the number of "borers in the panels, 

 so that the infestation wets Just as severe proportionately in the 2-inch 

 panels as it had been in the 1-lnch panels. As increasing the thickness 

 of the panels did not prolong their life, it was decided to shorten the 

 period of submergence and infestation to which the panels had been exposed. 

 Consequently, all panels which were on the test boaxd were removed on 

 November 19, and a riew set, operated on a U-month basis instead of the pre- 

 vailing 8-month basis, was installed. 



Teredinidae occurred in unusual abundance in all the control panels, 

 which is conclusive evidence that the breeding season at this location is 

 continuous. In these panels, 15 of the kO were from 50/^ to 100^ filled, 

 and specimens were recorded up to 50 mm in length. All the test panels 

 showed Teredinidae ] 55 of the h'J were filled or riddled, mostly after only 

 k months' submergence, and in one case, after only .2 months' submergence. 

 Specimens were recorded up to 190 nmi in length after 5 months' submergence. 

 The attack of Teredinidae was extremely severe each year. 



2. Limnoria . Limnoria were active throughout the period covered by 

 the test and occurred in every month of the year, but never in particularly 

 destructive numbers. They occurred in 5^ of the i»-0 control panels, 110 

 tiinnels being the maximum number recorded in any panel. In the test panels, 

 they occurred in 42 of the ^7, the attack rating slight in 19^5 and 19^6, 

 with a peak low in the moderate rating in 19^7 • 



5. Pholadidae . Pholadidae ( Hiata and Martesia ) likewise were 

 more or less active throughout much of the period covered by the test. In 

 the control panels, they occurred in 12 of the kO, but were only embryonic 

 or minute. However, 2 of these panels, which had been submerged in 19^6 

 from July 19 to August 19 and from August 19^ to September l8, respectively, 

 were half filled. They occurred in "^k of the ^7 test panels, and specimens 

 were recorded up to 17 ram in length. Three of these panels removed at 

 monthly intervals from August 19 to October 18 in 19^6, after having 

 been submerged for h months, were 75^> ^l1° and 55^ filled, respectively. 

 The attack by Pholadidae rated heavy in 19kk and 19^6 and medium heavy 

 In 19^5 and 19^7. 



A25.0it- Fouling Agents 



1. Silt . Silt occurred as traces to light or occasionally heavy 

 deposits on all the panels of botli the control and test series. 



2. Algae . A trace of a green alga occurred on one panel each of 

 the control and test series. 



109 



