2 HOYLE, Genera of Recent Dibranchiate Cephalopoda. 



Owing to the almost exclusive use of external 

 characters the arrangement here given does not always 

 follow grounds of morphological consequence; in several 

 instances owing to some exceptional character forms occur 

 out of their proper order. The discrimination by this key 

 presupposes the examination of adult specimens in good 

 condition ; the identification of young or fragmentary 

 examples can only be accomplished by careful comparisons. 



In order to furnish the reader with a survey of the 

 classification adopted I give at the outset a list of the 

 families recognized and of the genera included in each. 

 References to descriptions and figures will be found in my 

 " Catalogue of Recent Cephalopoda " {Proc. Roy. Phys. 

 Soc. Edinburgh^ vol. 9, p. 205 — 267, 1886) and "Supplement, 

 1887 — 96" {op. czt.,vo\. 12, p. 363 — 375, 1897) ; subsequent 

 works so far as they relate to new genera, are given in the 

 "Notes" (see p. 17). 



OCTOPODA. 



CiRROTEUTHiDiE : — CirroteutMs, Stauroteuthis, Froekenia, Opis- 



ihoteuihis. 

 AmphitretidtE :— Amphitretus. 

 Alloposii>^ : — Alloposus, Bolitaena. 

 ARGONAUTiDiE : — Argonauta, Ocythoe, Tremoctopus. 



PolypodiDjE : — Polypus, Tritaxeopus, Pinnoctopus, Clsfopus, 

 Scaeurgus, Moschites, Hoylea, JSledonella, 

 Japeiella, 



DECAPODA. 



Myopsida. 

 Idiosepiid^ : — Idiosepius. 



SepioliDjE : — Sepiola, Itiioteuthis, Euprymtia, Stoloteuthis, 



Heteroteuthis, Necioteuthis, Sepioloidea, 



Sepiadarium, Rossia, Semirossia, Pro- 

 niachoteuthis. 



