THE CEPHALOPODA. 205 



HI. — Shell lance-shape, slender, with central keeled ridge, and side expansions of some 

 length. Family, Gonatid^. One fossil genus, Loligo. 



5. LoiJGO, Lamarck, 1799. 

 Liassic. 



IV. — Shell lance-shape, subovate, with central ridge, and side expansions of some length. 

 Family, Beloteuthid^. Five fossil genera, Teudopsis, Phylloteuthis, Belo- 

 teuthis, Geoteuthis, and Leptoteuthis. 



6. Teudopsis, Deslongchamps, 1835. 



Narrow at top, enlarged below, with a concavity at base, and narrow central rib ; 

 Liassic into Oolite. 



7. Phylloteuthis, Meek and Hayden, 1858. 



Narrow at top, enlarged below, with slight concavity at base, where the lateral 

 margins are obtusely angular ; Cretaceous. 



8. Bei.oteuthis, Miinster, 1843. 



Pointed at top and bottom, lateral expansions forming a sudden angle on the sides 

 towards the lower half of total length ; Liassic. 



9. Geoteuthis, Miinster, 1843. =: Belemnosepia, Agassiz, 1835. = Loligosepia, 

 Quenstedt, 1839. = Coccoteuthis {jjars), Owen, 1855. 



Wide at top, pointed at base, side expansions forming a sudden angle on the sides 

 towards the upper half of total length ; Liassic. 



10. Leptoteuthis, von Meyer, 1834. 



Wide and rounded at top, pointed at base, lateral expansions gradually angular, 

 ribs slight and diverging ; Oolitic. 



V. — Shell ovate, thick, with thin lateral projections, incHned to the sides, terminating in 

 a projecting point imperfectly chambered. Family, Sepiad^ (Owen, 1836). 

 One fossil genus. Sepia. 



11. Sepia, Linne, 1735. = Belosepia, Voltz, 1830. = Sepiolithes, Miinster, 



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