TY  - GEN
AU  - Walcott,Charles D.
TI  - Cambrian geology and paleontology: II. No. 6. Middle Cambrian Branchiopoda, Malacostraca, Trilobita, and Merostomata 
PY  - 1912///
CY  - Washington : 
PB  - Smithsonian Institution, 
ER  -