44 8EX1 AL ORGANS, 



those of Loligo that he h:is examined, were found to carry a 

 greater OF less <iuantity <>t' spermatophores arountl their nioutli. 



Steenstrup lias shown (Ann. Mny. \<i/. ///*/., -2 ser., \\. is.'iT) 

 that whilst the OCtOpods (which nfimr arc known to lose their 

 copnlatory arm) possess in the highest decree the power to 

 reproduce mutilated members: the decapods, on thecontrary, are 

 not able to remedy Mich losses by a new growth : and this is an- 

 other cogent reason lor believing that the process of I'ccnndat ion 

 is entirely different in the two groups. Steenst.nip state,- that 

 the hectocotyli/ed arms, so I'ai 1 as he can ascertain, present no 

 changes at the season oi' copulation, thai they present the same 

 features in small as in large individuals: and he assumes that 

 when the young male leaves the egg it is already I'lirnished with 

 the hectocotyli/ed arm proper to its species. 



Brann 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 mollnsk found by 

 Quoy and (iaimard at the Celebes Islands ( Ann. SV. AV//.. \\, 

 470, 1-S30) may bi i the llectocot^ylus of tlie long-souiiht male of 

 Stinii.ln* pompilius. 



M. I'ssoxv obsei'ves that the sjmwning time of A rgonauta hi^tx 

 from May to August; of Loligo, Sepiola and Ommast replies, 

 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." Ann. MIUJ. A'. //.. 1 ser.. \v. 

 1875. 



I have figured a few forms of egg-clusters ( PI. 11), i>n. 1 ) ; 

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

 our knowledge is confined to the dihranchiates. Of these the 

 nio>l curious is the Argonaut, the elegant shelly structure of 

 which originates from the expanded dorsal anus of the 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 lonn. thin 



