400 DISCOVERY REPORTS 



Argonautid sex dimorphism or the peculiar hectocotylus. The dimorphism and 

 hectocotylus are not described in A. pacificus or in the East Atlantic forms described by 

 Joubin . On the whole this is not a very propitious situation for judging whether the various 

 specimens are congeneric with the type ! For the time being I think there is nothing to be 

 done but to be guided by "general facies" and to retain the forms described by Joubin, 

 Hoyle, Sasaki and Berry in Alloposiis, pending an examination of the type of A. mollis. 

 A. hardyi differs from A. mollis (Verrill's description, loc. cit. and 1881) in (i) the 

 shape of the mantle-aperture, (2) length of the web, and (3) disposition of the suckers. 

 Furthermore, if we utilise Joubin 's description, it differs in (4) details of radula, 

 (5) mandibles, (6) length-ratio arm i : arm 4. It differs very clearly from ^.^acz/zcws in 

 (i) radula {q-v), (2) general build and proportions, (3) length of arms (relative and 

 maximum length), and (4) number of gill lamellae. I have excluded from this discussion 

 the very remarkable rotation of the velar area (comparable to that found in Retroteuthis), 

 as I am not wholly satisfied as to the origin of this feature. 



