197 



detailed descriptions and figures given on suhsetiuent pages in order to confirm 

 identifications made liy use of the key. 



Throughoul the sNstematic treatment, subgeneric distinctions ha\-e been avoided 

 as meticulous. 



1. Pallets simple genus TEREDO 



2. Blade of jiallets approximately equal to, or longer than, stalk. 

 3. I )istal portion of blade sharply marked off froni basal portion. 



4. Distal portion of blade consisting of a solid capsule 



Teredo siimoaensis 



A' . Distal portion of blade leathery. 



5. Leathery portion of blade investing o\al calcareous base as a 



cap Teredo diege?isis 



5'. Leathery portion ending in 2, 3, or 4 irregular finger-like pro- 

 jections Teredo affinis 



V . Distal portion of blade not sharply marked off from basal portion. 



6. Distal pf)rtion of blade slightly narrower than basal portion 



Teredo aavalis 



6'. Distal portion of blade decidedly Ijroader than base. 



7. Stalk ending in an expanded knob Teredo mindanensis 



V. Stalk club-shaped, not knoblied Teredo trulliformis 



2'. Blade of pallets shorter than stalk. 



8. Blade almost completely in\ested with a hea\\ , tlark epidermis 



Teredo parksi 



8'. Blade not invested with a dark epidermis. 



9. Distal half of blade invested with a yellow, horny epidermis 



Teredo bartschi 



9'. Blade entirely calcified, either perfectly white or with a light 



yellowish distal portion Teredo furcillatus 



1'. Pallets compound, made up of reduplicated elements genus BANKIA 



10. Pallets symmetrical, more or less feather-like in appearance. 



IL Margins of separate elements drawn out laterally into slender pro- 

 jections connected by <i membrane Bankia setaeea 



11'. ALirgins of separate elements cut off abruiitK'. without lateral pro- 

 jections or membrane. 

 12. Separate elements closely crowded together, their margins much 



fimbriated both within and without Bankia orculti 



12'. Separate elements not closely crowded, their margins only 



slightly fimbriated Bankia mexieana 



10'. Pallets asymmetrical, wholly or partly covered within and without by a 

 periostracum Bankia excolpa 



Genus TEREDO 

 Teredo navalis Linn. 



Shell. Anterior lobe of moderate size; auricle variable, typically sub-triangular, but often semi- 

 circular or sub-quadrate, its length being typically about one-half that of the median lobe. The size 

 of the auricle appears to bear an inverse relation to the width of the anterior lobe (cf. figs. 110-111). 

 Color white, often washed with brown, especially from dorsal to ventral across the middle median 

 portion, and sometimes on the auricle. 



Pallets. Spatulate, extremely variable in outline, but typically symmetrical, blade urn-shaped, 

 widening regularly from a stalk of medium length, then tapering somewhat toward the tip, which is 

 decidedly exca\'ated. The base of the blade is calcareous, but approximately the distal third is normally 

 covered by a yellowish or brownish chitinous epidermis. 



