16 U.S. NATIONAL MUSEUM BULLETIN 234 



8. Dorsal and ventral lateral membranes of club not approaching at base of 



club, but becoming parallel along stalk .... Sepia pharaonis (p. 20) 



Dorsal and ventral lateral membranes of club closely approaching or united 



at base of club 9 



9, Lateral membranes of club nearly or completely united at base of club; 



one saw-toothed ridge or keel on three dorsal pairs of arms. 



Sepia prionota (p. 24) 



Lateral membranes of club completely united at base of club; no sawlike 



keel on three dorsal pairs of arms Sepia latimanus (p. 26) 



10. Tentacular stalk contained within both an oral and an aboral membrane 



which form a sheath about the stalk; body longer than wide, fins small; 



suckers in two rows throughout Sepiadariiim gracilis (p. 37) 



Tentacular stalks not contained within a sheath 11 



11. One or both dorsal arms hectocotyhzed in male; fins lateral 12 



Both ventral arms hectocotyhzed in male; fins terminal or nearly so. 



Idiosepius pygniaeus (p. 63) 



12. Mantle free from head in dorsal region; a papilla on each side of rectum 



below anus Rossia bipapillata (p. 40) 



Mantle united with head in dorsal region 13 



13. Two dorsal pairs of arms united by a web for half their length or more; 



both dorsal arms in male hectocotyhzed by a reduction in size of suckers. 



Sepiolina nipponensis (p. 42) 



Arms not deeply involved in the web; only left dorsal arm hectocotyhzed 



in males 14 



14. All arms normal in females; left dorsal arm hectocotyhzed by suckers of 



both rows on distal third or half with apertures nearly closed, shthke; 



suckers stalked, crowded together, palisaded 15 



Third arms of males and females curled inward; left dorsal arm hectocoty- 

 hzed in males by modification of the suckers in basal portion of arm . . 18 



15. Two rows of suckers on arms; left dorsal arm with only a few terminal 



suckers shthke in male; no specially enlarged suckers in male. 



Eupryixina phenax (p. 46) 

 Four rows of suckers on arms 16 



16. Suckers of ventral row in males enlarged, a few greatly so. 



Euprymna niorsei (p. 56) 

 Suckers of outer rows enlarged in males 17 



17. Suckers of outer rows much larger than those of median rows on left I, 



II, and IV. Suckers of III small throughout. 



Euprymna albatrossae (p. 49) 



Suckers of outer rows shghtly larger on left I and II; three or four suckers 



of ventral rows greatly enlarged; suckers of outer rows of IV much larger 



than those of median rows Euprymna stenodactyla (p. 52) 



18. Left dorsal arm of male hectocotyhzed by a large pocket in basal part of 



arm; ventral suckers of I, II, and IV greatly enlarged. 



Inioteuthis maculosa (p. 59) 

 Left dorsal arm of male hectocotyhzed by reduction in size of suckers on 

 distal two-thirds of arm and placement upon long pedicels, all with a 

 45° turn to right; basaUy, two long and one short pointed papillae on 

 ventral edge. Arms III much enlarged basally and strongly curled in- 

 ward Sepiola trirostrata (p. 57) 



19. Eyes covered by continuous skin of head, only a minute pore anteriorly; 



sucker rings toothed or smooth but never developed into hooks; shell a 

 broad tliin well-developed gladius. Suborder Myopsida 20 



