320 
PACIFIC SCIENCE, Vol. XVII, July 1963 
study continues. However, it is hoped that this 
discussion will make it easier to identify these 
animals in the field. I am grateful for financial 
support for this study which came in part from 
the American Academy of Arts and Sciences, 
and in part from the Mills College Faculty Re- 
search Fund. My thanks are here expressed to 
Dr. Joel Hedgpeth for helpful suggestions. 
FIELD KEY TO species OF Orchestoidea 
1. Mature animals 2 
1. Immature animals and others not distinguished by first part of key 5 
2. Second antennae when folded reaching back to or beyond middle of body; flagellum longer 
than peduncle 3 
2. Second antennae when folded not reaching back to middle of body; flagellum shorter than 
peduncle 4 
3. Color of 2nd antennae rosy-red calif orniana 
3. Color of 2nd antennae bluish-white columbiana 
4. Color of 2nd antennae usually salmon-pink corniculata 
4. Color of 2nd antennae not so 5 
5. Dorsal pigmentation pattern containing "butterfly” designs 6 
5. Dorsal pigmentation pattern containing T-shaped designs (Lower limb of T may be faint 
or missing) 8 
6. Mid-dorsal line absent, "butterfly” spots flattened X’s columbiana 
6. Mid-dorsal line present 7 
7. No markings on 3rd abdominal segment; sides of body relatively free of pigmentation 
marks calif orniana 
7. Markings on 3rd abdominal segment; sides of body blotched with checkerboard pattern 
...benedicti I 
.corniculata 
pugettensis Ij 
8. Two diffuse spots on sides of body.. 
8. Three discrete spots on sides of body. 
REFERENCES 
Bousfield, E. L. 1957. Notes on the Amphipod 
genus Orchestoidea on the Pacific Coast of 
North America. Bull. So. Calif. Acad. Sci. 
56(3): 119-129. 
1959. New records of beach hoppers 
(Crustacea: Amphipoda) from the Coast of 
California. Nat’l Mus. Canada Contr. Zook, 
Bull. 172:1-12. 
