PLATE LXXI. 
(Figures 1-3 copies ; 4, 5, 24-33 by 11. P. Whitfield ; (!-10,14-16, 34-38 by G. B. Simpson ; 11-13,17-23 by E. Emmons). 
Genus BAREANDELLA, gen. nov. 
Page 241. 
Barrandella linguifera, SoAverby. 
Figs. 1, 2. Dorsal and profile views of a normal individual; showing the character of the exterior and 
the well defined median fold on the brachial valve. 
Fig. 3. A longitudinal median section of the valves ; showing the small spondylium and extremely short 
median septum of the pedicle-valve, and one of the septal plates of the brachial valve. 
Wenlock limestone. Dudley, Enqland. 
(Figures 1-3 after Davidson ) 
Barrandella ventricosa, Hall. 
Figs. 4, 5. Front and dorsal views of a tyjiical example ; showing the fold upon the brachial valve, its 
faint plication, and the ca^fities of the median septa. 
Niagara dolomites. Waukesha, Wisconsin. 
Figs. 6, 7. Ventral and profile views of a ventricose specimen with a low sinus on the pedicle-valve. 
Figs. 8-10. Dorsal, profile and front views of a smaller individual having the fold and sinus distinctly 
plicate. 
Niagara dolomites. iVear Milwaukee, WiscoTisin. 
Barrandella fornicata, Hall. 
Figs. 11-13. Profile, dorsal and ventral views of the exterior of a specimen of average size ; showing the 
median fold on the brachial valve, the single broad plication in the sinus of the pedicle-valve, 
and the fainter plication of the lateral slopes. 
Clinton group. Lockpm't, Neio Yw'k. 
Barrandella Areyi, sp. fiov. 
Figs. 14-16. Dorsal, profile and ventral views, of a normal example ; showing the strongly plicated fold 
and sinus on the brachial and pedicle valves respectively, and the sharp plication of the lateral 
slopes. X 2. 
Clinton group. Mochester, iSfew Ycn-k. 
Barrandella Barrandii, Billuigs. 
Figs. 17, 18. Dorsal and ventral views of a large and typically developed individual; showing the broad 
plication in the median sinus of the pedicle-valve and the corresponding median groove on the 
opposite valve ; also the finer plication of the medio-lateral region. 
Figs. 19, 20. Dorsal and profile views of a smaller and more gibbous specimen. 
This species, in its earlier growth stages, is very similar in form and contour to £ fmmicata 
(figs. 11-13), but the rapid increase in size of the median plication in the sinus of the pedicle- 
valve, during the later growth stages of the shell, has the effect of reversing the relative 
position of fold and sinus in the final condition of gi'owth. 
Anticosti group. Bescie River, Anticosti. 
