1895. 



IN THE HOME OF THE NAUTILUS. 



411 



statement in Pelseneer's recent " Introduction a l'etude des 

 Mollusques," that " hyperpolygynie " occurs with the Nautilus, 

 requires modification. 



Most of the females that I have obtained have been immature, 

 whereas many of the males have been mature, and have had 

 spermatophores in the Needhamian vesicle and motile spermatozoa 

 in the testis, and, in rarer instances, I have found a spermatophore in 



Extreme of Difference. 



M 

 g 

 > 



r 



w 



Minimum of Difference. 

 Fig. 1. Secondary sexual characters in shells of Nautilus pompilius. 



the angle formed by the buccal mass with the dorsal hood, attached to 

 the innermost tentacles of the inner lobes of the cephalic tentacular 

 system, as first described by Van der Hoeven. There are reasons for 

 thinking with Van der Hoeven that the spermatophore remains here 

 for a long time. 



Van der Hoeven and Keferstein describe a difference in the 

 dimensions of the hood in male and female. I have made a large 



2 g 2 



