SQUILLOIDEA. g 2 



1. Species with a medio-dorsal spine, either on the 

 posterior margin or more or less remote from it. 



a. Having a large medio-lateral spine. 



1. Medio-post. spine stout, carapax short. 1. E. aculeatus, Edw. 



2. Medio-post. spine stout, carapax long (to fifth 



joint of abdomen). 2. E. tectus, Edw. 



3. Medio-post. spine small, very remote from pos- 

 terior margin. 3. E . Edwardsii, E. & X 



b. Having a small medio-lateral spine. 



1. Medio-post. spine small, marginal. 4. E. vitreus, Desm. 



2. Medio-post. spine small, distant from margin. 5. E. Leachii, E. & S. 



c. Having no medio-lateral spine. 



1. Medio-post. spine stout; post, margin straight. 



* Post, margin of carapax over fourth abdo- 



minal segment. 6. E. triangularis, Edw. 



** Post, margin hardly reaching abdomen. 7. E. spiniger, Dana. 



2. Medio-post. spine stout; post, margin at middle 



excavate. 8. E. armatus, Leach. 



3. Medio-post. spine small ; post, margin straight. 



* Latero-post. spines divergent, long. 9. E. 6-spinosus, E. & S. 



10. E. armatus, E. & S. 

 ** Latero-post. spines parallel; c.arapax to 



fifth abdominal segment. 11. E. vestitus, Dana. 



2. Species without a medio-dorsal spine. 

 a. Having a posterior medio-dorsal tubercle near or on 

 margin. 



1. Eostrum more than twice as long as inner an- 

 tennas. 12. E. longicornis, Edw. 



2. Eostrum very short, not longer than inner an- 

 tennae. 13. E. Duvaucellii, Ghtir. 



I. Without a medio-dorsal tubercle. 



1. Latero-anterior spines large. 14. E. pyramidatus, Edw. 



2. Latero-anterior spines small [sides of carapax 

 nearly parallel]. 



* Carapax not covering any abdominal seg- 

 ments; caudal segment oblong. 15. E. narwal, Guir. 



** Carapax covering first abdominal segment; 

 caudal segment not oblong. 



f Penult abdominal segment with two 



small teeth. 16. E. Latreillii, Guir. 



ft Penult abdominal segment without 



teeth. 17. E. GrUERiNii, E. & S. 



*** Carapax covering more than two abdo- 

 minal segments. 18. E. palliatus, Dana. 



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