EXPLANATION OF THE PLATES. 
425 
Fkl G. . Acrothele MattheAvi mut. lata. Mag. — a Ventral valve, 
interior ; has two pits in front of the foramen, diverging- 
arched ridges on each side of the foramen, and a low ridge 
on each side of the foramen extending to the hinge line • 
— h A dorsal in profile, showing the position of the hinge- 
line. From Protolenus Beds (C.16), Hanford Brook, N. B. 
See p. 402. 
Plate XVIII. 
Fiu. 1. Acrotreta sipo n. sp. — Section of ventral valve. Mag. 
See p. 406. 
Fig. 2. Acrotreta sipo. — Interior of dorsal valve. Mag. f. See p. 
406. 
Fig. 3. Bellerophon insulce n. sp. — Sinistral side. Mag. f. See p.. 
408. 
Fig. 4. Bellerophon Bretonensis n. sp. ; — a Dextral side ; — h Broken 
valve, showing interior, etc., both natural size ; — c Dor- 
sum, showing the angle of the growth lines. Mag. \ ; — d 
Part of surface of body whorl. Mag. See p. 409 
Fig. 5. Bellerophon semisculptus n. p. — Showing the outer whorl. 
Mag. f. See p. 410. 
Fig. 6. Urotheca sp. — Tube showing the larval part and the living 
chamber. Seep. 411. 
Fig. 7. Farabolinella quadrata n. sp. — Middle piece of the head- 
shield; Natural size. Seep. 411. 
Fig. 8. Triarthus Belli n. sp. — Middle piece of the headshield, left 
side and occipital ring restored. Mag. |. See p. 412. 
Fig. 9. Angelina ? sp. % — Larval cephalic shield. Mag. See p. 413. 
Fig. 10. Asaphellus Homfrayi^ Salter, var.; — a Adult, broad 
form partly restored ; h Middle piece of the head shield of 
the narrow form ; — c The hyposteme. All natural size; — d 
Early larval form, mag. ^ ^ later larval form, 
mag. f^. See p. 413. 
Fig. 11. Asaphellus {^\) planus. Adult. Natural size — the pygidium 
enlarged from another example supposed to be of this 
species. See p. 419. 
