44 SEXI.AL OU<;ANS. 



those of Loligo that he has examined, were found to carry a 

 greater or less quantity of spermatophores around their mouth. 



Steenstrup has shown (Ann. Mag. Nat. Hist., '2 ser.. xx, 1857) 

 that whilst the octopods (which alone are known to lose their 

 copulatory arm) possess in the highest degree tin- power to 

 reproduce mutilated members; the decapods, on the contrary, are 

 not able to remedy such losses by a new growth ; and this is an- 

 other cogent reason for believing that the process of fecundation 

 is entirely different in the two groups. Steenstrup states that 

 the hectocotylized arms, so far as he can ascertain, present no 

 changes at the season of copulation, that they present the same 

 features in small as in large individuals; and lit* assumes that 

 when the young male leaves the egg it is already furnished with 

 the hectocotylized arm proper to its species. 



Braun has supposed the aptychi to be the shells of the males 

 of Ammonites, instead of opercula ; this would explain why they 

 are so often found at the base of the first chamber of Am- 

 monites. 



It is also possible that the fragment of a mollusk found by 

 Quoy and Gaimard at the Celebes Islands (Ann. /SV. .\af.. xx, 

 470, 1H30) may be the Hectocotylus of the long-sought male of 

 Nautilus pompilius. 



M. Ussow observes that the spawning time of Argonauta lasts 

 from May to August; of Loligo, Sepiola and Ommastrephes, 

 from March to June ; but he has obtained mature ova of Sepia 

 in Naples almost all the year round, except in August. Ussow. 

 "Development of Cephalopoda, 7 ' Ann. M<j. A. //., 4 ser., xv, 

 L875. 



I have figured a few forms of cgg-cluslers (1*1. 19,20.22); 

 unfortunately the eggs of the Nautilus are not known, so that 

 our knowledge is confined to the <li)>raiichiates. Of these the 

 most curious is the A rgonaut, the elegant shelly si rticfnre of 

 which originates from the expanded dorsal arms of 1 he female 

 which cover its sides and form the only attachment of the animal 

 to it. In the unoccupied hollow of the spire are attached the 

 minute clustered eggs, and its special function appears to be for 

 their protection during development. Kadi egg is separately 

 enclosed in a rounded shell, which is furnished with a long, thin 



