CEPHALOPODA. 9 



entirely at the will of the animal. The receptacle of the ink is seat- 

 ed in the liver ; the glands of the oviducts are small. Some of them 



Polypus, Aristotle. 

 Have two alternate rows of cups along each foot. 



The common species, Sepia octnpodia, Lin., with a slightly 



Genus Renulina . 

 .... Cristellaria. 

 . . . Orbiculina . 



Third Family. — Les Cristac^es. , 



Miliola 1 



Gyiogona > Fourth Family. — Les Spheruldes 



Melonia J 



Rotalia -v 



Lenticulina \ Fifth Family. — Les Radiol^es , . 



Placentvila .... J 



{ Shell semidiscoid; mul- 

 tilocular, %vith sim- 

 ple septa ; the spire 

 eccentric. 

 rShell globose, multilo- 

 I cular, with simple 

 I septa, spheroidal or 

 <^ oval ; the whorls of 

 I the spire enveloping, 

 'i or the chambers uni- 

 L ted in a tunic. 

 /-Shell discoid, multilo- 

 ! cular with simple 

 I septa, spire central, 

 J chambers lengthened 

 j and discoid, extend- 

 l ing from the centre to 

 (_ the circumference. 

 ' Shell discoid, spire cen- 

 trical, cells short, 

 and in a spiral line 

 not extending from 

 the centre to the cir- 

 cumference. The 

 greater number are 

 fossil species. The 

 septa, as in the pre- 

 ceding genera, sim- 

 ple, neither notched 

 nor undulated on the 

 internal partition of 

 the testaceous exte- 

 rior. 



■ Shell multilocular ; sep - 

 ta sinuous, lobed, 

 and cut in their con- 

 tour, uniting toge- 

 ther against the in- 

 ternal partition of 

 the shell, and arti- 

 culated in sinuous 

 sutures divided and 

 dentated. Most of 

 these are known only 

 l^ in a fossil state. 



Second Division. — Ciphalopodes-monothaJames. — Navigators. 



{Shell unilocular, alto- 

 gether external, and 

 enveloping the ani- 

 mal. 



Discorbis . . 

 Siderolites .. 

 Polystomella 

 Vorticialis . . 

 Nummulites 

 Nautilus .... 



• Sixth Family. — Les Nautilac^es 



Ammonites.. ., 

 Orbulites . . . , 

 Ammonoceras. . 

 Turrilites . . . , 

 Baculites . , . . 



■ Seventh Family. — Les Ammon^es ^ 



