92 JOURNAL OF MARINE ZOOLOGY AND MICROSCOPY. 



long custom has united them under the old term Tetrabranchiata. 

 Hence I propose the division of the Cephalopoda into the Endo- 

 COclllia and the Ectocochlia^ ; the first including the Belemnitida3, 

 Sepiada?, Teuthidae, and Spirulidse ; while the second includes the 

 Nautiloidea, the Ammonoidea, and the Octopoda. This division not 

 only agrees with the trend of recent investigation, but also has the 

 merit of relying on a character which can be actually examined in 

 fossil, as well as recent animals. 



P.S. — Since the above was written, my attention was called to a 

 paper by MM. Perrier and Rochebrune, (Comptes Rendus CXVIII, 

 p. 770), in which they describe a new Octopus (0. dignati) from 

 California, which deposits its eggs within the shells of bivalves 

 (Cytherea and Pecten) and not only so, but itself gets into the shell 

 and remains there during incubation, and possibly longer. This may 

 be taken merely as a specialization of the ordinary habit of European 

 Octopi which utilize in like manner the crevices of rocks, and any 

 other hollow, as has been described by Aristotle, Lee, &c. But it 

 seems more likely to be a return to former habits. The Octopus in 

 the process of loosing its ammonitic shell, passed through a stage in 

 which some retained their original covering while others were free ; 

 some of the latter, then, during the sexual period, would feel the loss 

 of the shell which their near relatives possessed, and like the hermit- 

 crab, would take to their cast off shells if they could find them, or, 

 in default, any shell that came handy. From these are descended 

 the Californian species. Others, under peculiarly luxurious sur- 

 roundings lost the habit of covering their body altogether, and when 

 harder times set in, only a vague reminiscence of the instinct 

 remained, and they sheltered their eggs in any convenient hollow. 

 On any other hypothesis than the derivation of the Octopoda from 

 the Ammonites, the incubation of the Octopus is an inexplicable 

 mystery. 



(a), extos, without ; svtos, within ; y.oy\os, a shell. 



^^&^m^^^ s M& 



Ponds And Rock-pools.— Under this attractive title, Mr. Hy. Scherren has 

 gathered together, in pleasant form, many valuable notes on the smaller life that 

 swarms in tiny tidal reservoirs and among the weeds of country ponds. The hook 

 is just what such a work should aspire to be, and will be read with thorough 

 enjoyment by all true Nature-lovers. And while popularly written, the author 

 sacrifices no scientific truths, and draws upon personal experience in all things. 

 The price of this little work, which is published by the Religious Tract Society, is 

 extremely moderate. 



