46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



8. ex. 6.) Enlargement of the filaments of one of the thoracic 



exopodites in which the filaments retain their original round, 

 slender tubular form. This is the only specimen among 

 several hundred that I have examined which has escaped 

 flattening by compression. This is due to the pyritization of 

 the filaments of this particular specimen. 



9. (X4-) Ventral view of a specimen illustrated to show what 



appears to be a small oval flattened lobe attached to the 

 dorsal side of a protopodite or it may be to the proximal 

 joint of the exopodite; a number of the thoracic exopodites 

 with the filaments projecting forward occur on both sides, 

 also fragments of the large postero-lateral spines of the 

 carapace which lie above the exopodite of the thoracic limbs. 



Plate 23 



PAGE 



Helmctia cxpansa Walcott 38 



Photograph of the holotype. 



