ORDER It AMMONOIDEA 549 
Bactrites, Sandb. (Fig. 1120). In this, the only genus, the shell is straight, 
gradually tapering, and round or compressed elliptical in section. Devonian. 
Family 2. Nautilinidae. (Nautilini, Beyrich, pars). Mimoceracones and am- 
moniticones, rounded . _ - 
or more or less quad- ; : : 
rangular in section. 
Sutures have narrow 
saddles on either side 
of the undivided 
ventral lobe, and 
broad lateral lobes 
with saddles at the 
lines of involution or 
on the umbilical 
zones, when the latter 
are differentiated. 
Antisiphonal lobe 
absent. Dorsum with 
a broad azygous 
saddle. Aperture 
with a deep and 
narrow  hyponomic 
sinus, crests on the 
ventro-lateral angles, 
and broad lateral Fic. 1120. 
sinuses on either side. — Buctrites_—_ elegans, 
Mimoceras, Hyatt a Hee Sane sat 
(Fig. 1121); Anar- Eifel. A, Conch, 1/;. ioe 2 
. Moi Fi B, Suture-line, °%/; Anarcestes plebejus, Barr. sp. Lower Devonian (Btage 
cestes, ojs. (Figs. (after Sandberger). , |G); Hlubocep, Bohemia (after Barrande). 
1122, 1123); Prolo- 
bites, Karp.; Agoniatites, Meek (Aphyllites, p.p. Mojs.), (Fig. 1124); Palaeogoniatites, 
gen. nov. Type P. (Gon.) litwum, Barr. sp. Devonian. 
wh 

Fic, 1121. 
Mimoceras compressus, Beyr. sp. Lower Devonian ; 
Wissenbach, Nassau. A, B, Natural casts, 1/}. C, 
Nepionic individual enlarged. 



i 
i 
Ne 
it 
co 

n BS 

Fig. 1123. 

Anarcestes subnautilinus, Fic. 1124 
Schloth. sp. Middle Devonian ; area ; 
Wissenbach, Nassau (cf. Fig. Agoniatites occultus, Barr. Lower Devonian (tage G); 
1094). Hlubocep, near Prague, Bohemia (after Barrande). 
Family 3. Aphyllitidae. Frech. Ammoniticones with truncated venters. 
Sutures similar to those of Nautilinidae, except that a dorsal azygous lobe is present. 
Aphyllites, Mojs. Type A. ambigena, Mojs. Dorsal sutures unknown,  Pura- 
phyllites, gen. nov. Type P. (Gon.) tabuloides. Dorsum of this, involute form is 
