6 



BULLETIN 122, UNITED STATES NATIONAL MUSEUM. 



With the information furnished by the above outlined inquiry, it 

 should be easy to determine to what extent any form may become a 

 menace, for past efforts to overcome other obnoxious organisms have 

 repeatedly shown that when the full life history of the creature in 

 question was made known, ways and means were easily devised to 

 hold it in check, and shipworms should prove no exception to this 

 rule. 



SYSTEMATIC TREATMENT OF THE; GROUP. 



Exterior and interior of shell to show the terminology used in the descriptions. 



A. Anterior part. a. Anterior portion of median part. U. Umbones. 



M. Median part. m. Middle portion of median part. B. Blade. 



P. Posterior part. p. Posterior portion of median part. K. Knob. 



A KEY TO THE GENERA AND SUBGENERA OF THE FAMILY TEREDIDAE. 



Pallets consisting of a series of cone-in-cone structures Bankia. 



Coue-in-cone elements entirely free at their distal end. 



Distal ends of the cones terminating in a thin membrane. 



Membrane of the cones fimbriated distally Bankia. 



Membrane of the cones not fimbriated distally. 



Membrane of the cones denticulated distally Neobankia. 



Membrane of the cones not denticulated distally. 



Membrane of the cones entire distally Bankiella. 



Cone-in-cone elements not entirely free at their distal end. 



Cones almost fused on the outside where they are covered by a thick 



periostracum Nausitora. 



Pallets not consisting of a series of cone-in-cone structures. 



Pallets stilt-shaped * Bactronophobus. 



Pallets not stilt-shaped. 



Pallets paddle- or spoon shaped. 



Pallets paddle-shaped Tekedo. 



Terminal portion of the blade cupped. 



Cup single Teredo. 



Cup not single. 



Cup rendered double by a median septuixi-Teredothyra. 



^'As yet not reported in American waters. See plate 35. 



