SQUILLOIDEA. 625 



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

 posterior margin or more or less remote from it. 



a. Having a large inedio-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. TECTXJS, Edw. 



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

 terior margin. 3. E. EDWARDSII, E. & S. 



b. Having a small medio-lateral spine. 



1. Medio-post. spine small, marginal. 4. E. VITREUS, Dcsm. 



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. AR.MATUS, Leach. 



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



* Latero-post. spines divergent, long. 9. E. G-SPINOSUS, E. & 8. 



10. E. ARMATUS, E. & 8. 



* Latero-post. spines parallel; carapax 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. Rostrum more than twice as long as inner an- 

 tennae. 12. E. LONGICORNIS, Edw. 



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

 tennas. 13. E. DUVAUCELUI, Guer. 



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, Guer. 



'* Carapax covering first abdominal segment; 

 caudal segment not oblong. 



")" Penult abdominal segment with two 



small teeth. 16. E. LATREILLII, Guer. 



ft Penult abdominal segment without 



teeth. 17. E. GUERINII, E. & S. 



''* Carapax covering more than two abdo- 

 minal segments. 18. E. PALLIATUS, Dana. 



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