PLATE XXXII. 
Zone of Aegoceras Henleyi. 
Fig. 1. Aegoceras i.atecosta, Sowerby. Lateral view, natural size, from tlie original 
type specimen in the Sowerbian collec- 
tion. British museum. This fossil is 
the middle-aged condition of Aegoceras 
Henleyi before the transformation takes 
place (see PI. XXXIII). 
2. ■ — BREVispiNA — Lateral view, natural size. Original type. 
Sowerbian collection, British Museum. 
3. — — — Siphonal area of the same, showing the 
ventral row of short spines. 
4. — — ■ — Accurate tracing of the lobe-line. 
5. — Birch 1 1 — Small shell, showing details. My collec- 
tion. 
6. — — — Pront view, showing spines in profile, 
7. — — — Accurate tracing of the lobe-line, showing 
the smallness of the siphonal lobe and the 
magnitude of the principal lateral lobes. 
8. — — — Young forms of this species. The series is 
intended to show, in connection with 
PI. XXIII, that Aegoceras BircJiii main- 
tained its original form and structure 
through the various phases of its life. 
