PLATE XXIL 
Zone of Arietites obtusus. 
Fig. 1. Arietites sTELLARis, /Sbwer^y. Side view, natural size. British Museum. 
2. — — — Siphonal area, with keel, channels, and shell 
structure. 
3. — — — Another specimen, showing lobe-lines in situ. 
4. — — — ■ Front view of same fossil. 
5. — — — Siphonal area of same fossil. 
6. — — — Lobe-lines, lobes, and saddles magnified. 
The fossil shells figured in this plate all belong to the Sowerbian type collection in 
the British Museum. The smaller specimens (figs. 3, 4, 5, and 6) were those figured in 
the ' Mineral Conchology,' and are specially marked with Sowerby's green ticket. 
