PLATE XV. 



SILURIAN SPECIES. 



Fig. 



1 — 2 c. Atrypa mart/ in alls, Dalman. Figs. \, \ a, \ b, \ c, nat. size. 2 a, b, c, the same, 

 considerably enlarged. Wenlock limestone, Dudley. 

 1 d, a portion of the shell enlarged, to show the close 

 concentric lines or ridges. 

 3 — 8. Atrypa imbricaia, Sow. 3 and 3 a, nat, size ; Wenlock limestone, Dudley. 



4 a, b, c, a specimen considerably enlarged ; Dudley. 

 ^d, a portion of shell still more magnified. 5, 5 a, 6, 

 6 a, two flatter varieties. Wenlock limestone, Dudley. 

 7, a large old specimen from the Caradoc limestone. 

 Chair of Kildare ; Mus. Geol. Survey, London. 8, 

 nat. size, from Penkill, near Girvan, Ayrshire, 

 9 — IL Pentamerus ? rotundus {Afr7/pa rofunda, ^Qiw.). 9, 9 «, 9 b, drawn from the 

 specimen originally figured in ' Sil. Syst.,' pi. xiii, fig. 7. 

 Wenlock limestone, Wenlock Edge ; Mus. Geol. Soc, 

 London. 9 c, 9 d, the same enlarged. 10 — 10 r, a 

 larger specimen, from the Woolhope limestone, near 

 Malvern ; Worcester Nat. Hist. Museum. 11, another 

 specimen ; same locality ; Collection of Dr. HoU, 



12. „ „ ? Liternal cast of the ventral valve of a specimen so 



named by Prof. M'Coy. Kilbride, Cong, County Galway. 

 Sir R. Griffith's Collection. 



13 — 22. Pentamerus galeatus, Dalm. A series of specimens, showing the principal 



modifications in form assumed by this very variable 

 species ; all derived from the Wenlock limestone and 

 shale near Dudley. Figs. 15, 15 a, are after Sowerby's 

 illustration, ' Sil. Syst.,' pi. xii, fig. 4. 



23, • „ „ Profile view of the interior, one half of the valves having 



been removed. 



