rLATIi II— Coutinucil. 



BARROISELLA, gcii. nov. 



Page 62. 



Barroisella subspatulata, Meek and Wuillieii. 



Fi^'. 14. The cardinal portion of the i)eiiicle-valve ; showing the conspicuous pedicle-groove, which, in this 

 instance, luis been somewlmt widened by compression and fracture ; also the ai-ticular bosses 

 or (.ardinal fulcra on the biu^al margin. X o- 



Fig. 15. The interior of a iiedicle-VJilve ; showing the cardinal area, muscular and other markings. X H. 



Fig. 16. The inteiior of a brachial valve, with characteristic features. X 3. 



Black slate (Genesee slate). IVIiite River, near Rnckford, Indiana. 



LIXGULASMA, Uluicii. 



Page 2*. 

 LiNGULA-SMA SCHUOHERTI, Ullicll. 



Fig. 17. The apical portion of the internal cast represented in tig. 22 ; enlarged to show the impression of 

 the pedicle-sheath (ps), or internal continuation of the cardinal aren. X 3. 



Fig. 18. The inteiior of a brachial valve : showing the character of the muscular impressions, the platform 

 and the very strong septum. Ui-awn from a gutta-per<tha impiession of an internal cast. 

 Natural size. 



Fig. lit. Profile view of an internal cast ; showing the relative thickness of the platforms on the two valves. 



Fig. 20. The interior of the pedicle-valve ; showing the pedicle-slieatli (ps), the indistinctly cletined muscu- 

 lar impressions, the low platform and inconspicuous septum. This drawing is also made from 

 a giitta-pereha impression. Natural size. 



Fig. 21. An enlargement of the surface ornamentation. The tubercles are sharply detiued, and round on 

 the median jiortions of the shell, but become elongated and less distinct toward tlu^ lateral mar- 

 gins. X 5. 



Fig. 22. A natural cast ; showing iKe inteinor of the brachial valve. 



Fig. 23. The oppo.site side of the same specimen; sliowing the intei'nal characters of the iieilicle-valve. 

 Hudson River group. Wilmington, Illinois. 



LfNGULOPS, Hall. 



Page 18. 



Ling I LOPS Nokwoodf, James. 



Fig. 24. The exterior of a pedicle-valve. X 4. 



Fig. 2.^. The interior of a pedicle-valve, drawn from a gutta-percha imjuession of a natural cast. The 



pedicle-groove is faint but evident ; within the broad posterior mai-gin lie the compound um- 



lional or cardinal impressions ; the scalloiied posterior and the median mu.scular scars are very 



sharply detiued. X S. 

 Pig. 21!. The interior of a brachial valve ; sliowing tlie low, elongate platfoini. The punctje on the surface 



of the platform appear to be regularly arranged l)ut are jnobably aci'idental markings. 



Diawn iVorn a gutta-pei'cha impression. X 6. 



Hudson River group. Cincinnati, Ohio. 



L1NUULOP8 Whitfieldi, Hall. 



Fig. 27. The exterior of a pedicle-valve. X 6. 



Fig. 28. The interior of a pedicle-valve ; the original specimen. The figure has been drawn from a gutta- 

 percha imi)ression of an internal cast, and sliows the compound cardinal area (seen also in tig. 

 30). the inner jKirtion of which is concentrically striated ; the crescent (ci') ; the scalloped pari- 

 i^tal s(!ar and median muscular scars ; the narrow longitudinal septum Hanked by broad, rounded 

 ridges continued from the visceral regiim. No traces of va.scular impre.ssions are visible on 

 the specimen. X 12. 



Fig. 29. An impei-fect interior, (U'obably belonging to the same (pedicle-) valve. X 12. 



Fig. 30. The interior of the brachial valve, drawn fi-om a gutta-percha impression ; showing the double 

 I'arilinal nw.ii, a faint pediclc-depres.sion, the crescent (cr), tlii^ pari(?tal ('.) scai-s, the platform, 

 and the va.scular sinuses with their outer ramitications. X 10. 



Hudson Rivei- group. Maqiiokela Creek, 12 miles north-west of Ditliiique, fmca. 



