CLASS V 



CEPHALOPODA 



629 



Bactrites Sandb. (Fig. 1169). In this, the only genus, the shell is straight, 

 gradually tapermg, and round or compressed elliptical in section. Devonian. 



Family 2. Nautilinidae Hyatt {NauUUni Beyrich, 'pars). 



Mimoceracones and 

 ammoniticones, rounded 

 in section. Body- 

 chamber long. Sutures 

 have narrow saddles on 

 either side of the un- 

 divided ventral lohe, 

 and hroad lateral lohes 

 with saddles at the lines 

 of involution or on the 

 umbilical zones, tvhen 

 the latter are differen- 

 tiated. Antisiphonal 

 lobe absent. Dorsiim 

 with a hroad azygous 

 saddle. Aperture with 

 a deep and narrow 

 hyponomic sinus, crests 

 on the ventro - lateral 

 angles,and hroad lateral 

 sinuses on either side. 



Mimoceras Hyatt „ . •. 



,„. , , _^s > Bactrites eleyans 



{rig. 1170); Anarcestes Sandb. Upper De- 

 Moi'? ('Fi CT« 1171 anrl vonian ; Büdesheim, 



Mojs. (^rigs. ii/i ana ^j^^j .4, Conch, i/.- 

 111^); ProlobitesKdiV^. b, Suture- 



ß 



Fig. 1169. 



Fig. 1170. 

 Mimoceras comp^ressum (Beyr.). Lower Devonian : 

 Wissenbach, Nassau. A, B, Natural moulds, Vi- C 

 ^epionic individual enlarged. ' 



Devonian. 



line, 

 (after Sandberger). 



Fig. 1171. 



Anarcestes pleb^us (Barr.). Lower Devonian (^tage G) ; 



Hlubocep, Bohemia (after Barrande). 



Family 3. Aphyllitidae Frech. 



Ammoniticones with truncated venters, compressed whorls and short body -Chambers. 



Fig. 1172. 



Anarcestes subnautilinu: 

 (Schloth.). Middle Devonian 

 Wissenbach, Nassau. 



Fio. 1173. 



AgoniatUes orcultus (Barr.). Lower Devonian (Etage G) ; 

 Hlubocep, near Prague, Bohemia (after Barrande). 



Sutures similar to those of the Nautilinidae, except that a dorsal azygous lobe is sometimes 

 present. 



