295 



somewhat puzzling. Its distrilmtii)n in tiie bay has thus far buen limited to a small 

 inlet about one mile north of South San Francisco. It was discovered here in 1920 by 

 Professor Kofoid, in submerged bracing timbers under the marine ways of the Schaw- 

 Batcher .Shipbuilding Corporation (on the premises of the Western Pipe and Steel 

 Company). A thorough search during the succeeding years has not revealed this 

 species as occurring at any other point in the bay, and its numbers at this one locality 

 where it has been found appear to be considerably depleted at the present time. An 

 inspection of piling and brace timbers here on June 21, 1924, revealed onh- a few 

 specimens of this organism, in company with more numerous Teredo navalis, and test 

 boards placed at this time showed only a very light and scattered attack of Teredo 

 diegensis when e.xamined in September following. 



There appears to be no ciuestion that the organism under discussion is true Teredo 

 diegensis, and identical with that species as occurring in Los Angeles and San Diego 

 harbors, although the San Francisco Bay specimens have been described by Bartsch 

 (1922) as Teredo townsendi new species. We ha\e compared large numbers of specimens 

 from all three localities, and find that the differences in the pallets which Bartsch has 

 considered to be of specific — and even sub-generic — value, are merelv individual 

 variations within the species. We have found typical diegensis, and the variate called 

 townsendi, occurring invariably together at all localities where either has been reported, 

 and it is usual to find these two variates, together with several intergrading forms, 

 in the same piece of timber. 



Characteristic diegensis has dark tipped, truncated pallets. The form which has 

 been described as townsendi dififers merely in having the distal portion of the blade 

 exca\-ated. Either form, on drying, may de\-clop a distal corona such as Bartsch has 

 described as typical of diegensis. 



Considerable variation occurs in the color of the distal corneous portion of the 

 pallet, which may vary from pale, transparent amber through deep brown to black. 

 This variability is only in part an age character, although as a rule the periostracum 

 becomes thicker and hence darker with increasing age. It often occurs, howe^-er, that 

 in quite small specimens from the California coast the distal portion of the blade is 

 decidedly dark. In specimens from the Hawaiian Islands, on the other hand, the 

 corneous portion of the pallet remains quite transparent in specimens four or five 

 months old. Whether or not the darker color later de\elops we do not know, as older 

 specimens ha\-e not been a\-ailable from the test blocks. On dr\ing, the distal peri- 

 ostracum of the pallets of the insular diegensis becomes darker and more opaque, so 

 that the pallets are hardly distinguishable from those of the California coast. 



The darker corneous portion of the pallet is not infrequently partly or wholK' 

 worn away or broken otT, in which case the blade of the pallet is represented simpl\- 

 by the oval calcareous base (fig. 12, 2 and 3). The corneous portion can be rather 

 readily removed from normal pallets, thus reducing them to the oval form. 



We conclude that Teredo diegensis is particularly a pest of the warmer waters of 

 the coast of southern California and the Hawaiian Islands. It has in some manner 

 been introduced to San Francisco Bay, and has in a measure established itself in a 

 small inlet near South San Francisco, where the shallow water becomes sufficiently 

 warmed to permit the organisms to breed at least during the summer months. The 

 history of the species in San Francisco Bay during the four years in which it has been 

 under observation suggests that it is here able only to eke out a struggling e.xistence 

 under conditions to which it is not well adapted. It appears at present unlikeh- 

 that this species will occasion serious damage in San Francisco Bay or harbors to the 

 northward. 



