CLASS V 



CEPHALOPODA 



629 



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

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



Family 2. Nautilinidae Hyatt (NauUlini Beyrich, pars). 



Mimoceracones and 

 avimoniticones, rounded 

 in section. Body- 

 cJiamber long. Sutures 

 have narroio saddles on 

 cither side of the un- 

 divided ventral lohe, 

 and broad lateral lohes 

 iDith saddles at the lines 

 of involution or on the 

 umbilical zones, tvhen 

 the latter are differen- 

 tiated. Antisiphonal 

 lobe absent. Dorsum 

 with a broad azygous 

 saddle. Aperture with 

 a deep and narrow 

 hyponomic sinus, crests 

 on the ventre - lateral 

 angles,and broad lateral 

 sinuses on either side. 



Mimoceras Hyatt 



Fig. 1170. 



iMiiiwcerds coviprcfsiuii (Beyr.). Lower Devonian ; 

 Wissenbach, Nassau. A, B, Natural moulds, i/j. C, 

 Nepionic individual enlarged. 



Fig. 11(59. 



Ikwti'ites 



clrijdns 



Fiu. 1171. 



(Fig. 1170); Anarcestes Sandb. Upper De- 



Ar • /XT'' iit-ri „^l vonian ; Budesheim, 



:\rojs. (Figs. 1171 and ^^^^^^ j, Conch, i/,: 



1112)' ProlobitesK.a,V\). J>, Sutm-e - line, s/j Anarcestes plehejus (\i^n.). Lower Devonian (Etage G) ; 



^ ". ^' (after Sandberger). Hlubocep, Bohemia (after Barrande). 



Devonian. 



Family 3. Aphyllitidae Freeh. 

 Ammoniticones icith truncated venters, compressed whorls and short body -chambers. 



L EL 



Fig. 1172. 



.1 narcpstes subnautilin us 

 (Schlotli.). Middle Devonian ; 

 Wissenbach, Nassau. 



Fig. 1173. 



Agoniatites occultus (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. 



