398 



DISCOVERY REPORTS 



result of this rotation is that, if we imagine the animal orientated with its oral surface 

 downwards in the traditional horizontal plane of the Cephalopod, the mantle aperture 

 instead of being posterior has become dorsal. This is exactly what has happened in 

 Joubin's Retroteuthis and also in his Heptapus (Joubin, 1929 Z>, p. 13). In that genus 

 Joubin failed to find any indication that the condition is anything else than normal. In 

 this instance I am in practically the same position. Not only is the posture of the body 

 altered in relation to the oral surface, but the web has definitely become concrescent with 

 the dorsal tissues, and ventrally it has become elongated, apparently as a result of (or to 

 meet) the pressure imposed on it by the backward rotation of the visceral mass and head. 

 I do not think this can be caused by accidental distortion or pressure. On the other hand, 

 this form is very gelatinous, and I am not quite clear as to what distortion might occur when 

 a rather heavy gelatinous organism of this kind is kept permanently on a hard surface. 



Fig. 17. Alloposus hardyi. x c. 1-5. 

 (Semi-diagrammatic.) 



Fig. 18. Alloposus hardyi. Radula. 



If the rotation is normal, its origin is very obscure. The animal was taken near the 

 surface in water of a depth of 1600 fathoms and must therefore be pelagic. The modifica- 

 tion can have no relation, as far as I can see, to crawling on the bottom, and in any case 

 the normal Octopod posture is suited to this. It is noteworthy that Retroteuthis, which 

 also shows a similar modification, is quite remotely allied to A. hardyi. 



The suckers tend to be uniserial or very widely alternating except about and just 

 beyond the margin of the web where they are more or less biserial. They are very 

 prominent but small (6-2 per cent of the mantle length) and extremely weak. Like those 

 of A. mollis (Joubin, 1900, pi. v, fig. 14) they are simple, undifferentiated cups, but the 

 walls are everywhere thinner in A. hardyi. 



The mantle aperture is as in Alloposina microcotyla (Hoyle, 1904, p. 9) shaped like a 

 flat W. Its pallial edge is non-adherent. The funnel is mainly incorporated in the head, 

 but there is a free tubular portion about 8-10 mm. long. The shape of the funnel-organ 

 is obscure. Unlike the other forms there are a number of longitudinal folds near the 

 aperture, below which are the remains of what may have been a W-shaped funnel-organ. 

 The gills have six to seven filaments in each demibranch. 



