272 BULLETIN OF THE BUREAU OF FISHERIES. 



4'. Dorsal arms of female connected by a broad velum, but without terminal expansions; no 

 external shell; right third arm of male hectocotylized ; aquiferous pores present on head. 



Tremoctopus violaceus, p. 281. 

 3'. No aquiferous pores; no external shell; dorsal arms normal. 



6. Body soft and gelatinous; suckers in two rows; hectocotylus of male involving entire 



right third arm, which is presumably separable Alloposus mollis, p. 287. 



6'. Body soft; suckers in a single row; hectocotylized arm not separable (family Boli- 



t<Bnid(E) Eledonella sp. , p. 289. 



6". Body comparatively firm; suckers in two rows; hectocotylus of male confined to tip 

 of one third arm, to which it forms a spoon-shaped extremity. (Family Polypodidce.) 

 7. Hectocotylus affecting third arm of right side. (Genus Polypus). 

 8. A conspicuous pigmented oculation obliquely in front of each eye; hectocotylus 



minute Polypus marmoratus, p. 291. 



8'. No definite ocular markings in front of the eyes. 

 9. Adult brightly colored, the pigment conspicuously arranged in longitudinal 

 bands or series of spots; arms very long and attenuate. . .Polypus ornaius, p. 294. 

 9' '. No definitely arranged color pattern. 



10. Body smooth, without cirri; second arm pair longest; color dark. 



Polypus hawaiicnsis, p. 290. 

 io'. Body finely papillose, rather soft, with blunt cirri over the eyes; mantle 



opening small; color uniformly pale Polypus hoylei, p. 296. 



Y . Hectocotylus affecting third arm of left side ; body bounded by a conspicuous periph- 

 eral fold Scceurgus patagiatus , p. 305. 



II. Arms normally 10 in number, one pair being greatly modified to form the "tentacles"; suckers 

 distinctly pedunculate, their apertures usually bounded by a chitinous ring (Decapoda). 

 1. Eyes covered by a continuous membrane (division Myopsida). 



2. Adult small; body short, rounded posteriorly, with round or ovate lateral fins; gladius much 

 reduced or wanting. (Family Sepiolids.) 

 3. Dorsal margin of mantle fused with head in nuchal region. 



4. Fins of moderate size; suckers in four rows on the arms and 16 or more on the tentacle 



club; left dorsal arm hectocotylized Euprymna scolopes, p. 312. 



4' '. Fins very broad and longer than the mantle; suckers on the arms in two rows; a conspicuous 



shield-shaped patch on the ventral surface of the mantle Sloloteuthis iris, p. 316. 



3'. Dorsal margin of mantle free; funnel covered by a conspicuous forward prolongation of the 



mantle Heleroleuthis hawaiiensis , p. 319. 



2' '. Adult relatively large; body elongate, pointed posteriorly; fins marginal, extending the entire 

 length of the mantle; gladius well developed, its texture horny throughout. 



Sepioteuthis arctipinnis, p. 308. 

 1' '. Eyes with a perforated lid (division OEgopsida). 



5. Part of the suckers with their chitinous rings transformed to hooks. 

 6. Sessile arms with true suckers only; one or more rows of hooks on tentacle club. 

 7. Adult moderately large; two rows of hooks on the tentacle club. 



Onychoieuthis banksii, p. 322. 

 Y ■ Adult small ; hooks and suckers of tentacle club in four rows. 



Teleoteuthis compacta, p. 324. 

 6'. Sessile arms with part of the suckers modified into hooks. (Family Enoploteuthida.) 

 8. All suckers of sessile arms modified into hooks except at the extremity; hooks also 

 present on tentacle club ; ventral surface of mantle ornamented with numerous 

 photogenic organs. 

 9. Buccal membrane pale in color; tips of ventral arms normal. 



10. Photophores of mantle distinctly of two types and showing a definite bilateral 

 arrangement; fins comparatively small Abralia aslrosticta, p. 326. 



