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4 rows of suckers

30a. Suckers on tentacular club in 4 longitudinal rows; mantle free dorsally (Fig. 63)...... Family Cycloteuthidae

30b. Suckers on tentacular club in 8 or more longitudinal rows; mantle fuseddorsally to head (Fig. 64) ...... Family Promachoteuthidae

10b. Funnel fused to mantle on each side; no funnel-mantle locking apparatus present

31a. Mantle free dorsally, articulates with head by ridge and groove (Fig. 65...... Family Grimalditeuthidae

31b. Mantle fused dorsally with head tentacular (Fig. 66)...... Family Cranchiidae club 1b. Eight circumoral appendages (arms only) ventral view Cycloteuthidae (Discoteuthis)Fig. 63 32a.Suckers stalked (with chitinous rings); internal shell a chitinous, thin, broad, plate;a pair of small filamentous circu- moral appendages in pouch between bases of arms I & II; light organ (photo- phore) present at base of each fin and medial to each eye dorsally; colour black (Fig.67 ) ...... Order Vampyromorpha (monotypic order)

32b.Suckers sessile, without stalks and with- out chitinous rings; internal shell ves- tage either small cartilaginous rods or a U-shaped support; secondary filamen- tous appendages and light organs absent; colour to dark maroon, but never black...... Order Octopoda

tentacular club

ventral view Promachoteuthidae (Promachoteuthis)Fig. 64

filaments

ventral view dorsal view dorsal view Cranchiidae Vampyromorpha Grimalditeuthidae (Vampyroteuthis) (Grimalditeuthis) (Mesonychoteuthis) Fig. 67 Fig. 65 Fig. 66 light organs - 23 -

33a. Cirri present on arms

34a. Secondary web present; body elon- gate with prominent head; shell vestige saddle-like (Fig. 68) ...... Family Cirroteuthidae

34b. Secondary web absent; body flat- tened along dorsoventral axis; shell vestige straight or slightly bent (Fig. 69) ...... Family Opisthoteuthidae cirri and suckers 33b. Cirri absent on armsseen through trans parent web 35a. Body gelatinous

36a. Suckers on arms biserial (Fig. 70) ...... Family Alloposidae

36b. Suckers on arms uniserial ventral view Cirroteuthidae (Cirrothauma) Fig. 68 (Fig. 71)

37a.Stomach posterior to “liver” (= digestive organ) (Fig. 71) ...... Family Bolitaenidae

37b. Stomach anterior to “liver” (= digestive organ)

38a. Mantle opening reduced to 2 small lateral slits; eyes, elongate, tubular (Fig. 72)...... Family Amphitretidae

top view Opisthoteuthidae (Opisthoteuthis) Fig. 69

1 row of suckers

2 rows of suckers

dorso-lateral view lateral view ventral view Amphitretidae () Bolitaenidae () Alloposidae (Alloposus)

Fig. 72Fig. 71 Fig. 70 - 24 -

38b. Mantleopening wide; eyes small (Fig. 73) ...... Family Vitreledonellidae

35b. Body firm

39a. Water pores present (Fig. 74)

40a. Water pores present both dorsally and ven- trally web very deep; surface of mantle smooth, unsculptured (Fig. 74) . . . . . FamilyTremoctopodidae

40b. Water pores present ventrally only; web greatly reduced; surface of mantle heavily sculptured with tubercles in a reticulate pattern (Fig. 75)...... Family Ocythoidae

39b. Water pores absent; web normal, reduced or absent

41a. Males very small (smaller than females); hectocotylus (left third arm) temporarily coiled in sac below eye, with extremely long filamentous tip; females with dorsal arms I each with broad, membranous lateral view flap that secrets and holds a thin, shell-like Vitreledonellidae () egg case (Fig. 76)...... Family Argonautidae Fig. 73 41b. Males with left or right third arm hectoco- tylized (never in pocket); with spoon- shaped, non-filamentous tip; females with- out dorsal arm flaps; egg case always absent (Fig. 77)...... Family Octopodidae

shell covered with membrane water of first arm pores

dorsal view Tremoctopodidae (Tremoctopus)

Fig. 74

lateral view lateral viewof female Ocythoidae (Ocythoe) Argonautidae (Argonauta)

Fig.75 Fig. 76

dorsal view Octopodidae ()

Fig. 77

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