86 CEPHALOPODA. 



resembles Tarrilites in shape, but the sutures are simply 

 lobed and are not foliaceous. 



In the genus Hamitcs (fig. 473, /) the shell is an ex- 

 tremely-elongated cone, which is bent upon itself more than 

 once, in a hook-like manner, all the volutions being separate. 

 Numerous species of Hamitcs are known, all of them being 

 Cretaceous, and ranging from the Lower Greensand to the 

 Chalk. Hcmiulina, of the Cretaceous, has the shell bent once 

 upon itself, as in Ptychoccras, but the reflected portions of the 

 shell are not in contact with one another. 



In the genus Ptychoccras (fig. 473, a) the shell is also a 

 much-elongated cone, which is simply bent upon itself once, 

 the two straight portions of the shell being in contact. The 

 range of this genus is the same as that of Hamitcs, extending 

 from the Lower Greensand to the Chalk. 



Lastly, in the genus Baculitcs (fig. 4:73, h and c) the shell 

 is simply a straight elongated cone, not bent in any way. 

 Baculitcs corresponds, therefore, with Ortlioceras in the series 

 of the Ncmtilidcc. The range of Baculitcs is the same as tliat 

 of the preceding — from the Lower Greensand to the Chalk ; 

 but the cenus is most aljundant in the Chalk itself. 



