PLATE LXX. 



(ngurag 1, i, 4-14 by K. Emhons ; 3, copy.) 



Genus PENTAMERUS, Sowerby. 



I'age 436. 



Pentamerus oblongus, Sowerby. 



See plates Ixviii, Ixix. 



Vif. 1. Dorsal view of an internal cast of a broadly ovate shell, with evenly convex valves. 



Niagara dolomites. Near Milwaukee, Wisconsin. 

 Pig. 2. A natural lonjfitudinal section throug'h both valves ; showing the comparatively short median sep- 

 tum and septal plates, the projecting spondylium and crural processes. 

 Clinton irroup. Rochestifr, New York. 

 Fig. 3. A copy of the original figure of this species given by Mdrchisom in " Silurian System," plate xix, 



figure 10. 

 Fig. 4. Dorsal view of a large, elongate-.«ubovate shell, with trilobed surface, broadly shouldered urn- 

 bones and closely incurved and depressed ventral beak. 

 Clinton group. Rochester, New York. 



Pentamerus oblongus, vnr. subrectus, var. uov. 

 See plates Izviii, Ixix. 

 Fig. 6. A somewhat weathered specimen in which the valves have been displaced from their normal posi- 

 tion, exposing the spondylium of the pedicle-valve, and, by the removal of the rock, also show- 

 ing a part of the united septal plates of the brachial valve. This spondylioid condition of 

 these plates is a normal feature of this variety. 

 Niagara beds. Jones county, Iowa. 



Genus CAPP^LLINIA, gen. nov. 



Page 248. 



Capellinia mira, sp. IIOV. 



Figs. 6, 7. Ventral and cardinal views of an average specimen ; showing the predominant convexity of the 

 brachial valve, the smooth sui-fa(;e and the position and extent of the internal plates. 



Fig. 8. Cardinal view of another example in which the convexity and umbonal incurvature of the brachial 

 valve are still more conspicuously developed. 



Fig. 9. Cardinal view of a i>edicle-valve ; showing the inconspicuous, suberect beak and wide delthyrium. 



Fig. 10. Ventral view of the same specimen ; showing the length of the median septum. 



Fig. 11. Profile view of a normal individual ; .showing the relations of the valves. 



FigK. 12, 13. Ventral and profile views of anotner example in which the umbo of the pedicle-valve is ab- 

 ruptly depressed. 



Fig. 14. A brachial valve, showing the length of the septal plates and a low radial plication over the um- 

 bonal region. 



Niagara dolomites. Near Milwaukee, Wisconsin. 



