SUBCLASS II 



DIBRANCHIATA 



683 



guard. 



Fig. 1321. 



Diploconus helem- 

 nlUddra Zittel. Ti- 

 tlKuiian ; Strainberg. 



tion. Phragniacone only very slightly inserted in the guard, the two portions usually 

 separated by an interval. Middle and Upper Cretaceous. B. subventricosus Wahlb. ; B. 

 quadratus Blaiuv. 



BcleitinitcUa d'Orb. (Fig- 

 1320). Guard cylindrical, with 

 short, deep ventral furrow fall- 

 ing short of the alveolar margin. 

 Pliragmacone inserted in guard. 

 Vascular impressions often 

 beautifully preserved. Upper 

 Cretaceous. 



Diploconus Zitt. (Fig. 

 1321). Guard short, obtusely 

 conical, and having a con- 

 centric lamellar structure, not 

 radial and fibrous. Phragnia- 

 cone reaching nearly to the 

 posterior end of the 

 Tithonian. 



Bayatioteuthis Mun.- 

 Chalni. Guard long, cylind- 

 rical, mucronate, with shallow 

 lateral grooves. Dorsal area 

 roughened. Pliragmacone very 

 slender and long, oval in 

 section. Eocene ; Paris /Basin 

 and Ronca, Italy. B. rugifer 

 Schloenb. 



Vasscuria Mun. - Chaliii. 

 Guard slender, elongated - 

 conical, with a number of 

 longitudinal grooves extending 



from the apex. Pliragmacone more than one -half as long as the guard. Septa 

 oblique, their necks extending from one septum to the next. Very rare in the Eocene 

 of Brittany. 



Belemnosis Milne Edw. Very rare in the English Eocene. Styracoteiithis Crick. 

 Intermediate between Belemnitella and Bayanoteuthis. Eocene ; Arabia. 



Beloptera Blainv. (Fig. 1322). Guard short and somewhat swollen at its forward 

 end, which makes a slight angle with the pliragmacone ; on either side it is expanded 

 into a conical projection. Eocene. 



Belopterina Mun.-Chalm. Like Beloptera, but without the lateral wing-like 

 expansions. Eocene. 



Fig. 1320. 



licli'mnitcs (BclcmniteUa) mucronatua 

 Schloth. Upper Cretaceous ; Drenstein- 

 furtli, Westplialia. A, B, 0, Ventral, dorsal 

 and lateral aspects. %. 



Pig. 1322. 



Beloptera be.lcm- 

 nitoidai Blv. Calcaire 

 Grossier; Paris Basin. 

 Ventral aspect. 



Family 2. Beleninoteuthidae Zittel. 



Shell composed of a conical phragmocone and proostracum, the guard being reduced 

 to a thin calcareous or horny investment of the pliragmacone. Ten arms of nearly equal 

 length, each heset ivith a douhle roio of hooJcs. Ink-sac 'present. Trias and Jura. 



Acanthotcuthis Wagner and Miinst. {Belemnites Quenst. p.p. ; Ostracoteuthis Zitt.) 

 (Figs. 1323-1325). Pliragmacone with numerous septa, and siphuncle having short 

 siphonal funnels ; enveloped externally in a thin granular calcareous layer rej)resent- 

 ing the guard. Surface of proostracum divisible into a broad dorsal, and two narrow 

 lateral areas which are longitudinally striated and taper toward the front. Dorsal 

 area ornamented with fine parabolic and also straight longitudinal lines ; anterior 



