i \ i i u\ \i. IB 

 Tin- n- :MT n< nt In . >f I lie bod \ u liich are liable to pen* 



chant's in si/e ; and therefore, ad the position and pr- 



enlargement with a:T nt' tin- ^TiM-ratm- -i | >|>:i r:it n-, neCi 



ITsllIt-* like t host- seen ill t he chamber> :illl -sepia. | |vj;i|.| 



use of I li' <>t her." 



Prof. Keferstein decidedly agrees \vitli Woodward and oth< 

 th:M the adductor muscles of Nautilus cont inuou->l\ urow for- 

 wards, and are re-absorbed liehiud. rat her than suddenly moved 

 ,|)|>osed by d'Orbi^ny. 'Then i 1' these at I achiueiit s added to 

 that of the continuous horny vjrdle sullice to hold the animal to 

 it> position, the septum, as Woodward shows, would result from 

 a rest-period, and should at least be externally distinguishable 



anioiio the growth lines of the i-xterioi' sui'lace. In tliis c.-i-e. 

 Mr. Seely'^ theory I'alU. and tin- animal simply builds the septa 

 lo the ( 'ones, certain Uulimi. etc. 



It is nnlv the backs of the septa which are covered with mem- 

 brane, ami this membrane may be required to maintain the 

 vitality of the slu-11 in the deserted chambers. Keferstein also 

 con>iders it most, likely that, the siphon serves to ma inta in 1 he 

 purity of the air in the chambers. The Nautilus may -\\ini. 

 belli-- provided with a locomotiv tube or siphon, but it certainly 

 is not, well adapted by its structure for that mode of progression, 

 and probably prefers the sea-bed. ; Still, the specific liTavity of 

 shell and animal so nearly equals that, of the >ea-water that 

 probably the additional displacement caused by spreading out 

 to the utmost iN tentacles would cause if to rise in tiie water. 

 It is just possible that, when the Nautilus issues from its slu-11 

 the LTa-> contained in the last chamber in the rear of the animal 

 max expand, and so reduce the specilic uravitv. 



'flic siphunele is vascular, it opens into the heart-c-i \ it \ 

 (pericardium), and is most, probably tilled with lluid from it. 



Woodward says (Man. Moll., p. IN}): Tin- use of the air- 

 chambers is to i-cmlcr the whole animal (and shell) of nearlv the 

 6 ^pecilic uravity with the water. Thus :i Xnnl, 



Mi. A. S. IJirkinoif. wli<> <-i>llf<-ic(| Nautili at A inhoina. nl. 



that ii lias lircn commonly believed thai tin- Nautilus occasioiiall] 



to tin- ^urfaci-, a IK I " sett iii^ its sails. ll>ats >\cr the sea." 'I'll is \\;i> \\\-^\ 

 reported hy 1 {unijiliiiis, l.itt, after making continued ami careful iu.|ii; 

 lie had satistiei! liinixd!' that there i> ii" reason t> suji]M>e that the animal 

 tVnin the Led of the sea. /' V //., \,i. 



