Zoology.] NATUEAL HISTORY OF VICTORIA. IMollusca. 



All the shells, with their inhabitants, are females, and I have not 

 yet succeeded in finding the male ; which in this genus has all the 

 arms tapering, is very much smaller than the female, and without 

 shell. The Mediterranean shelled Argonauts usually have a 

 curious, swollen, detached arm of the male adhering to them, like a 

 parasitic worm, obviously having functions connected with the 

 fertilisation of the eggs, but formed into a supposed genus of 

 parasites, named Hectocotyle^ by Cuvier ; and these too have escaped 

 notice in the Australian examples. 



Like most of the eight-armed Cuttle-fishes, the Argonauts have 

 a short, thick, round body, without fins, and without any internal 

 hard parts, such as the so-called Cuttle-fish bone, or pen, of the 

 higher, ten-armed families. The eyes, as usual in this group, are 

 fixed immovably, and covered by the colored general skin, except 

 in front of the pupil. 



No one now beUeves the old idea that the shell, floating like a 

 boat on the surface of the sea, is rowed along by the dependent 

 slender arms, while the pair of broad arms are held up like sails 

 to propel it by catching a favorable wind, like an ancient galley. 

 The progress through the water is only eflfected by backward 

 starts, produced by ejecting water violently through the funnel, 

 the 3 anterior pairs of arms streaming out in a group in front, 

 while the shell, covered over by the expansion of the posterior or 

 superior pair, cleaves the water. 



Like all the Octopoda the Argonauts are generally nocturnal, 

 and inhabit the high seas, feeding on various floating small animals ; 

 rarely coming near the surface by day, except in calm weather. 

 The females only approach the shallow waters of the coast in 

 summer time, when the eggs are developed. It is in the hottest 

 months of summer (January, February, and March), especially in 

 the last few years, that they appear on the shores of Hobson's Bay, 

 near Brighton, where several specimens of the animal and shell 

 together have been obtained. The individual figured was given to 

 me alive by a young friend (who requested that his name should not 

 be mentioned), and was kept alive in a large tub of sea- water for a 

 considerable time. Nothing could be more ludicrously interesting 



Dec. VII. [ 9 ] B 



