81 



8 days, below 3., 18 days. Teredo survived at approximately the salini- 

 ties shown in the table at Carquinez Strait Light, and at Crockett near 

 the mud line in 14 feet of water where recent analyses show the sa- 

 linities to range from to 6 parts per 1000 higher than at the surface. 

 Since the intervals of 25 and 27 days in the table represent the inter- 

 val between the monthly spring tides, it is evident that Teredo sur- 

 vived for these periods in water of a salanity at no time above 4 or 5 

 parts per 1000, or adding 1 part for the distance to Carquinez Strait 

 Light, 5 or 6 parts per 1000, while in 14 feet of water at Crockett it sur- 

 vived for tensions of somewhat shorter periods. 



Specific Star us of the Teredo of San Francisco Bay 



The boring mollusk responsible for the extensive destruction of 

 piling in San Francisco Bay in 1917-20 was identified by us in our re- 

 port for 1920 as Teredo navalis Linnaeus, the well known pile worm of 

 European waters. It has since been described by Bartsch* as Teredo 

 bcachi, new species, but without designation of the characters which 

 differentiate it from Teredo navalis. We have not had specimens of 

 T. navalis from the U. S. National Museum for comparison, but through 

 the kindness of European specialists we have been able to obtain named 

 specimens of T. navalis from Plymouth, England, Copenhagen, Den- 

 mark, Helder, Holland, and Naples, Italy. Comparison of the T. 

 navalis from San Francisco Bay with these European specimens con- 

 firms our identification. Specimens from San Francisco Bay which we 

 haye sent to Paris have been identified by Dr. Lamy of the National 

 Museum of Natural History at Paris as T. navalis. Dr. W. T. Caiman, 

 specialist for the British Committee on Marine Structures, writes that 

 our figures are undoubtedly of T. navalis. 



The Pacific Coast has been ransacked for decades by conchologists 

 such as Cooper, Dall, Stearns, Williamson, Hemphill, the Oldroyds, 

 and many others, but no one found T. navalis. It was not met with 

 in the survey of San Francisco Bay by the U. S. Steamer Albatross, 

 nor in any of the extensive collections made by the Scripps Institu- 

 tion of the University of California in coastal waters of California. 

 Its behavior in Carquinez Strait in 1917-1920 and in 1921 is of such 

 intensity that it is highly improbable that it could have been present 

 in earlier years and have escaped notice- 

 It appears that there are thus sound biological grounds for re- 

 garding this Teredo as a new introduction from some other area of 

 distribution. Other introduced mollusks are well known in San Fran- 

 cisco Bay, such for example as Ih/annassa o~bsoleta Say. Additional 

 evidence that it is a new intruder arises from the fact that untreated 



*Bartsch. P. A. A new classification of the shipworms and descrip- 

 tions of some new wood-boring- mollusks. Proc. Biol. Soc. Washing-ton, 

 vol. 34, pp. 35-42. March 31, 1921. 



