6 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.18 



5. In species which develop ridges of pleon segment 2, it is found 

 that the female develops 2 lateral ridges, the male one medial ridge. 



6. Some species show striking differences in the morphology of uro- 

 pod 3. This is well seen in Ampelisca lobata Holmes. 



Artificial Key to the Species of Ampelisca Known From the 



Eastern Pacific Ocean 



1. Eyes present 4 



1. Eyes absent 2 



2. Posterolateral corner of pleon segment 3 rounded . plumosa 

 2. Posterolateral corner of pleon segment 3 produced into a 



tooth 3 



3. Coxae 1 and 2 with a tooth at posterolateral corner 



catalinensis 



3. Coxae 1 and 2 without tooth coeca 



4. Peraeopod 5, article 3 much longer than 4 . . milleri 

 4. Peraeopod 5, article 3 subequal to or shorter than 4 . 5 



5. Pleon segment 3 strongly rounded 6 



5. Pleon segment 3 quadrate or produced 12 



6. Pleon segment 4, dorsal surface strongly produced, poste- 

 riorly ending above segment 5 8 



6. Pleon segment 4 slightly convex, posterior end nearly flush 



with segment 5 7 



7. Peraeopod 5 and uropod 3 stout schellenbergi 



7. Peraeopod 5 and uropod 3 slender in structure . . . lobata 



8. Dorsal process of pleon segment 4 strongly saddle shaped 

 venetiensis 



8. Dorsal process of pleon segment 4 not saddle shaped . . 9 



9. Uropod 3, one ramus strikingly uncinate .... romigi 

 9. Uropod 3, not appearing uncinate in undissected animal . 10 



10. Uropod 3, peduncle short, stout, rami elongated . . .11 



10. Uropod 3, peduncle subequal to rami .... isocornea 



11. Pleon segment 4, process hood shaped in female . cucullata 



11. Pleon segment 4, process not hood shaped in female . vera 



12. Carina of pleon segment 4 lamellar 13 



12. Carina of pleon segment 4 not lamellar 14 



13. Dorsal edge of carina entire cristata 



13. Dorsal edge of carina incised cristoides 



14. Uropod 3, rami broad pacifica 



14. Uropod 3, rami slender, lanceolate 15 



