SUB-CLASS II DIBRANCHIATA 597 
Distribution world-wide ; most abundant in Europe, Asia, and North America. As 
an index fossil of the Jura and Cretaceous, 
this genus is scarcely less important than 
Ammonites. 
Sub-Genera : Pachyteuthis, Bayle (Fig. 1241, 4). 
Guard perfectly smooth. Confined to Lower Lias. 
B. acutus, Mill. 
Megateuthis, Bayle (Dactyloteuthis, Bayle ; 
Paxillosi), (Fig. 1241, B). Apex of guard with 
two or three usually short grooves. Middle Lias 
to Lower Cretaceous. B. paxillosus, LB. giganteus, 
Schloth. ; B. elongatus, Mill. ; B. subquadratus, 
Roem., ete. 
Belemnopsis, Bayle (Hibolithes, Montf. ; Gastro- 
coeli, Canaliculati, Hastati), (Fig. 1241, D, £). 
Guard with deep and usually long ventral furrow 
extending from alveolar margin toward the apex, 
with or without dorso-lateral lines. Middle Jura 
to Middle Cretaceous. B. canaliculatus, Schloth. ; 
B. absolutus, Fisch. ; B. wnicanaliculatus, Ziet. ; 
B. minimus, Lister. 

















Fia. 1241. 
vile dep Pentre) acutus, Miller. Lower 

Lias; Lyme Regis, Dorsetshire. B, B. (Mega- 
Fic. 1239 = teuthis) paxillosus, Schloth. Middle Lias ; Metzin- 
? Fic. 1240 gen, Wurtemberg. C, B. (Pseudobelus) bipartitus, 
Belemnites compressus. Lias ; Sian Bly. Lower Cretaceous; Castellane, Basses 
Gundershofen, Alsace. Belemnites (Duvalia) Alpes. a, b, c, Dorsal and ventral aspects and 
Phragmocone with well-pre- dilatatus, Blv. Neo- cross-section, 1/;. D, B. (Belemnopsis) canalicu- 
served conotheca. a, Asymp- comian; Justithal, latus, Schloth. Inferior Oolite; Wiirtemberg. 
totie line; h, Hyperbolic Lake of Thun, Switzer- E, B. (Belemnopsis) hastatus, Bly. Oxfordian ; 
area; v, Ventral area. land. Dives, Calvados. 
Pseudobelus, Montf. (Bipartiti), (Fig. 1241, C). Guard thin, slender, with deep dorso- 
lateral grooves, with or without ventral furrows. Upper Lias to Lower Cretaceous. B. exilis, 
dOrb. ; B. bipartitus, Blainv. 
Actinocamax, Mill. (Gonioteuthis, Bayle), (Fig. 1242). Guard cylindrical, submucronate, 
with short but very deep ventral furrow ; anterior end foliaceous, and very liable to dissolu- 
tion. Phragmocone only very slightly inserted in the guard, the two portions usually 
separated by an interval. Middle and Upper Cretaceous. B. subventricosus, Wahlb.; B. 
quadratus, Blainy. 
Belemnitella, d’Orb,. (Fig. 1243). Guard cylindrical, with short, deep ventral furrow 
falling short of alveolar margin. Phragmocone inserted in guard. Vascular impressions 
often beautifully preserved. Upper Cretaceous. 
