CEPHAloroBA. 201 



Hamites, Parkinson. 



Etymology, hamus^ a hook. 



Example, H. attenuatus (PI. III., Pig. 15). 



Shell hook-shaped, or bent upon itself more than once, the 

 courses separate. 



Distrihiition, 58 species. Xeocomian — Chalk. South A.merica 

 (Tierra del Puego), Europe, India. 



6 



a 

 Fig. 65. Sutures of Hamites cylindraceus, Defr.* 



The inner courses of this shell probably break a^vay, or are 

 *' decollated," in the progress of its gro^vth. (Forbes.) M. 

 D'Orbigny has proposed a new genus, hamulina, for the twenty 

 neocomian species. 



Ptychoceeas, D'Orbigny. 



Etymology, ptycJie, a fold. 



Example, P. emericianum, D'Orbigny (PI. III., Fig. 14). 



Shell bent once upon itseK; the two straight portions in 

 contact. 



Distribution, 8 species. Neocomian — Chalk. Britain, France, 

 India. 



Bactjutes, Lamarck. 



Etymology, haculus, a staff. 



Example, B. anceps (PI. III., Fig. 13). 



>S/jeZZ straight, elongated; aperture guarded by a dorsal process. 



Distribution, 17 species. Neocomian — Chalk. Europe, South 

 America (Chili), India. 



Baculina^ D'Orbigny, 2 species. B. Eouyana. Neocomian. 

 France. Sutures not foliated. 



The chalk of Normandy has received the name of haculite lime- 

 stone, from the abundance of this fossil. 



* Fig. 65. Space between two consecutive sutures of the right side, from a specimen 

 in the British Museiun. a, dorsal line ; b, ventral. Baculite limestone, Fresville. 



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