﻿PLATE XI. 



DEVONIAN SPECIES. 



Fig. 



I — 6. Atrypa desquamata, Sow. Lanes or Woolborougli Quarry. Collection of Mr. 



Vicary. Fig. 2, specimen from Plymouth, Geol. Soc. Mus., 

 showing portions of the laminal projections. Figs. 3 — 6, 

 different modifications in shape, from Woolborougli 

 Quarry. Pig. 3, Collection of Mr. Stewart. 



7. „ „ Interior of the dorsal valve, showing the spiral appendages. 



8. ,, „ Specimen from which the larger portion of the dorsal valve 



has been removed, in order to show the back of the 

 spiral coils. 



9. „ „ Interior of the ventral valve : f, foramen ; d, deltidium ; 



t, teeth ; a, adductor or occlusor ; r, ventral adjustor 

 muscular impressions ; v, vascular impressions. 

 10 — 12. flabeUata, Goldf. From Woolborough Quarry. Figs. 10 and 12, from 



the Mus. of the Geol. Survey. Fig. 11, Collection of Mr. 

 Pengelly. 



13. Davidsonia Verneuilii, Bouchard. Interior of the ventral valve; a large specimen, 



attached to a valve of String. Burtini, from Woolborough 

 Quarry. In the Collection of Mr. Vicary. 



14. „ „ Interior of ventral valve attached to Atrypa aspera, from 



Woolborough Quarry. Mus. Geol. Survey. 



15. „ ,, Interior of the dorsal valve (enlarged), showing the cardinal 



process, sockets, impressions of the adductor or posterior 

 , and anterior occlusor muscle. It also, on one side, shows 

 a restored representation of the spiral lamella?. 



16. ,, „ Interior of ventral valve (enlarged), showing the teeth, pseudo- 



deltidium, adductor and divaricator muscular impressions, 

 as well as the massive cones and vascular impressions. 



