MONOGRAPH OF AMERICAN SHIPWORMS, 29 



TEREDO (TEREDOPS) DIEGENSIS Bartsch. 

 SAN DIEGO SHIPWORM. 



Plate 22; fig. 3 ; plate 34, fig. 3. 



1916. Teicdo diegensis Bartsch, Nautilus, vol. 30, No. 4, pp. 47, 48. 



Shell small, subglobular, white. The anterior area rather heavy, 

 with the usual sinus which is edged with a strong callus slightly 

 reflected over the back of the shell, from which it is not strongly dif- 

 ferentiated. The rest of the anterior area is marked by dental ridges 

 which have a strong downward flexure a little distance from the ante- 

 rior edge, and then bend in an even curve backward, expanding 

 slightly fan-shaped. These ridges are almost as wide as the 

 spaces that separate them. There are 53 present in the type. 

 They seem to slope almost as abruptly on the venttal side 

 as on the dorsal, and are A-ery finely denticulated on the free 

 margin. The anterior median portion of the middle part is crossed 

 by strong dental ridges which are separated by mere impressed 

 lines and very strongly denticulated at the free edge. They join 

 those of the anterior part at right angles. The junction between the 

 anterior and median part is a slightly sinuous line. The middle por- 

 tion of the median part forms a slightly depressed groove which is 

 crossed by rough wrinkles. The posterior portion of the median part 

 is about as wide as the anterior and is marked bv strong; lines of 

 growth. The posterior part forms a minute auricle which is marked 

 by a series of obsolete corrugations which parallel the ventral mar- 

 gin. Interior bluish white. The junction of the anterior and the 

 posterior portion is marked by a tumid cord. The auricle extends 

 over the posterior median portion as a narrow shelf. The umbone 

 has a strong knob from which a broad, curved, and somewhat flexed 

 blade extends for a little more than half the width of the shell. The 

 ventral margin of the median portion bears the usual knob. The 

 pallet has a sinuous, cylindric stalk. The blade is subcordate in 

 shape. The distal portion is drawn out. The distal two-thirds are 

 covered by a strong periostracum, the outer portion of which bears 

 a strong calcareous knob at the tip. 



The type. Cat. No. 74219, U.S.N.M., was collected by Henry Hemp- 

 hill at San Diego, California, and measures : Height : 4.7 mm. ; length, 

 4.4 mm. ; diameter, 4.6 mm. The pallet measures : Length, 5.7 mm., 

 of which 3 mm. go to the stalk ; diameter 1.2 mm. 



There are four additional lots of this species in the United States 

 National Museum, all from San Diego. 



The peculiar pallets, the broad anterior median area, and the small 

 auricle will distinguish this at a glance from any of the West Amer- 

 ican forms. It is distinguished from Teredo {Teredops) floridana by 

 93044—22- -3 



