PLAT Hh ZV. 
(PEAY SCHISMAIMOC OVE oe se celen se sateen etre eee tela tee Pept acoso csecuscassceccoscs Saneen 
Figs. 1, ia, 1b. Summit, lateral, and basal view of a small specimen. Natural size. 
le. Longitudinal section of a larger shell. 
METOPTOMAS UD EVONICAW ce ser coca en cca teeainerioe close meats tee ene en eee eee aoe 
Figs. 2,2a. Lateral and anterior view of the type specimen. 
PLATYSCHISMA ? AMBIGUUM..---- .<--0- 220-00 0--n0- ones woe n en onan enw ree conn enw eees cones 5 
Figs. 3, 3a. Lateral and summit view of a silicified specimen. 
BEYRICHTA® (E>) \OCCIDENTADIS (eos sees ane meetin eee ie te ele nee eee eee 
Fig.4. Large size left valve, enlarged to four diameters 
4a. Enlargement of a young specimen (1™™) in length, to show the unisuleate char- 
acter at this stage of growth, x 12. 
VOY AE ee i Doe a og oe ESS Ga gene sooSe a Somes So goSeeD Hoee Ect DaseasSoseS postcns codessodesce 
Fig. 5. View of the glabella of a medium size specimen. 
5a, 5b. Dorsal and lateral views of a medium-size and large pygidium. 
5e. Enlargement of a portion of the surface of 5b, to show the punctate character 
of the test. 
BELLEROPHON) PERPUR KA se slem 2 ale wes leis miele tela aal se Pe eal ote a) laa eater S 
Fig.6. Transverse section, showing the deep, open umbilicus and flattened whorls. 
6a. Dorsal view, showing the dorsal ridge and the direction of the stria. 
6b. Longitudinal section, showing the closely coiled whorls. 
CyrTOCERAS NEVADENSIS ..-- .--- FERRIC ICTIO OAR U ode sac Sarn Sao uOn Rona SHODS aoe Se aeene sees 
Fig.7. Lateral view, showing the depth of the chambers and the curvature of the tube. 
7a. Ventral view of the same, with the surface striw preserved. 
GOMPHOCERAS|SUBOVIHORME ~coe on once as cee melon seat aeceen ome cen teniaams neimospesscsoasesec 
Fig.8. Ventral view, showing the chamber of habitation, air-chambers, and a portion of 
the siphuncle exposed by the weathering of the specimen. 
8a. Lateral view of the same. 
BELLEROPHON COMBSL cc. ooc- = ooo eee eecesis= === <= -/aenlonae PcO chro Sse ecodon sect SCO ASE S 
Figs.9,9a. Lateral and front view, to show the form of the species. 
GONTATITESIDESEDERATUS oiniste mma am mete mateo = 2) ate ete lot iol eae) otto al etate inl etalsferaie aie reas 
Fig. 19. Lateral view of a specimen preserving a portion of the surface strie on the inner 
volution. 
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