PLATE II. 



Leg-end. g. Umbonal scars. p. Pedicle-g'i oove. 



g'. Cardinal scars. ps. Pedicle-sheath. 



1 Lateral scars. d. Cardinal area, 



h. Central scars. cc. Cardinal callosities, 



c. Conci'ete centrals. Jil. Platform. 



z. External scars. s. Median septum. 



b. Parietal scai'. vs. Vascular sinuses. 



Crescent. 



LINGULELLA, Salter. 



Page 55. 

 LiNGULELLA C^LATA, Hall. 



Fig-. 1. A pedicle-valve, from which the shell is partiallj' exfoliated ; showing- ti-aces of the curved lateral 



"'I and the central scars. X 2. 



■Pig. 2. A pedicle-valve, retaining- most of the shell ; showing the surface ornamentation and the open- 

 ing of the foi-amen ; (a) longitudinal section, showing- the elevation of the beak ; (b) posteiior 

 elevation. X 2. " ^-'1 -;' 



Fig-. 3. A brachial valve ; showing the central and lateral muscular impi-essions, and a vevy sharply de- 

 '"' fined seal' (z) which, if not adventitious, maj' be homologous with the external scars in Obolella 



crassa, or the terminal crescent scai-s in the Trimerellids. X 2. 

 Fig. 4. An incomplete cast of the same valve. X 2. , 



Middle Cambrian. Near Troy, N.' T. 



LiNGULELLA DaWSONI, Muttliew. 

 Fig. 5. A cast of the interior of the pedicle-val\-e. X 3. 



St. John group. Portland, New Brunswick. 



LiNGULELLA (?) PALIEGRMIS, Hall. 



Fig. 6. A view from the dorsal side of both valves in normal juxtaposition ; showing the elevation of the 

 cardinal area in the pedicle-valve, and its pedicle-slit, which by compression appears tbrouo-h 

 the exfoliated apical portion of the brachial valve. X 2. ° 



Hamilton shales. Shurger's Qlen, Cayuga Lake, N. Y. 

 Pig. 7. A pedicle-valve , showing a faint slit along the position of the pedicle-groove. X 3. 



Hamilton shales. Pratt's -Falls, Onondaga county, N. Y. 

 Fig. 8. A pedicle-valve, which has been compressed along- the filling- of the pedicle-slit. X 3. 

 Hamilton shales. Sliwrger's Qlen, Cayuga Lake, N. Y. 



LiNGULELLA Stoneana, Whitfield. 

 (Lingulella aurora, var., Hall.) 

 Fig. 9. Dorsal view of a specimen. Natural size. 



Fig. 10. The same, enlarged to three diameters ; showing the characters of the cardinal area. 

 Fig. 11. An enlargement of the surface ; showing the concentric gi-owth-lines crossed by undulatino- lamel- 

 lose striae. ^ 



Potsdam sandstone. In the upper, variegated magnesian layers, near Mazomanie, Wis. 



, ^,.,;, LiNGULELLA AURORA, Hall. 



Fig. 12. A dorsal \-iew of the specimen ; showing the high cardinal area, and its pedicle-gi'oove. X 3. 

 Fig. 13. Anothei- specimen, similarly enlarged. 



Potsdam sandstone. Near Mazo^nanie, Wisconsin. 



