84 NATURAL SCIENCE. August. 



Sexual Characters in Nautilus. 



This question seems to be settled at last. Just a month after 

 our publication of Mr. Willey's important paper, with its illustrations 

 of the differences between the shells of the male and female Nautilus 

 pompilms, there appeared in the Comptes rendus of the French Academy 

 (vol. cxx., p. 1,431) a note by Dr. A. Vayssiere, of Marseilles, " Sur 

 le dimorphisme sexuel des Nautiles," which confirms and extends the 

 observations of Willey. In both A^. pompilius and N. macromphalus 

 the opening of the female shell tends to be laterally compressed, while 

 that of the male shell tends to be wide, especially towards the inner 

 side of the whorl. The shell of the female has also a slight tendency 

 to be keeled, and its margin is more sinuous than in the male, which 

 is the opposite of Van der Hoeven's statement. The difference of 

 width is clearly due to the size of the spadix, or copulatory arm of the 

 male, which is on the right of the buccal bulb, and thrusts the bulb a 

 little to the left ; thus this portion of the body becomes nearly as wide 

 as that at the level of the eyes. In an adult male the width of the 

 hood equals its length, so that it is two centimetres wider than in the 

 female ; its lateral margins almost entirely hide the eyes and tentacles 

 in the male, but in the female the eyes and first two pair of tentacles 

 are exposed. Dr. Vayssiere states that the mantle is not shorter in 

 the male than in the female, and supposes that Van der Hoeven said 

 it was. We have been unable to find any such statement in Van der 

 Hoeven's paper ; what he referred to was the hood, as correctly 

 quoted by Buckman and Bather in our own pages (vol. iv., p. 431), 

 and he was merely saying the same as Vayssiere, though in a different 

 manner. Buckman and Bather, while admitting the existence of 

 differences between shells of Nautilus, pointed out that the characters 

 of width and of sinuosity in the margin increased with age ; this is 

 confirmed by Vayssiere, who is, however, now able to show, with 

 Willey, that these differences are actually sexual characters. 



Applying these observations to the ammonites, Vayssiere shows, 

 as Buckman and Bather had already pointed out, that they are totally 

 opposed to the views of A. d'Orbigny, P. Reynes, and H. Douville, 

 and that they lend no support to the more complicated theories of 

 Munier-Chalmas. Here, too, our English authors have received 

 confirmation from Dr. J. F. Pompeckj in his study of Rhaetic 

 ammonites {Neucs Jahrbuch ftir Mineyalogie, 1895, ^^' •^^•' P- 4^)* ^^^ 

 own observations "completely agree" with their conclusion that 

 " the so-called males are in reality the final expressions of the 

 various races to which they belong." 



The Origin of the Cephalopods. 



It was an interesting paper that Mr. J. Graham Kerr read before 

 the Zoological Society on June 18. It emphasised the paired and 



