DEM Gye Od) D2) EE be 
ING GAS ON ENSIS ee Sates sina ele mete ae itt Aone ia ee sania a eliem cio'elcteinm|ceima males e\vniaiaiaeis 
Fig. 1. Ventral ? valve. 
la. Dorsal ? valve. Natural size. 
ISON CHCA LOE RYE Sop ae 55050 COGN SOS RES SUS ORD CSDCED SECU GEEOODRODEeD EE eG CSeeC Ube ECE eee 
Fig. 2. Ventral valve, from which the surface is largely exfoliated. Natural size. 
IDAHO, WEIN 3 S55 Co eSeS ae Sep Ens POSSE S BHEGED DADSC GE Heeb Og AC0D OOH OCdd Son ESo CeO eOOere 
Fig. 3. Cast of the interior of the dorsal valve, enlarged to two diameters. 
d. Divaricator muscular sear. 
ad, Adjustor muscular sears, 
pa. Posterior adductor sear. 
aa. Anterior adductor scar. 
pp. Supposed area of attachment of the posterior parietal muscle. 
wu. Supposed area of attachment of the walls of the perivisceral cavity. 
ps. Great pallial sinus. 
1s, Lateral branches of the great sinus. 
i. Area, that in another specimen shows the inner ramifications of the great sinus. 
The various features are rather strongly shown in the figure, but not more 
so than is justified by the original specimen. 
RKENTDIUM  DEVONIOCUM so ncles cicisain sees acc cee ncciee ss cissieie claw sale wlnwioeninincle vos clare cece secs 
Fig. 4. Ventral valve, enlarged to three diameters. 
4a. Cardinal view, showing the areas of the two valves, the foramen, and the medium 
septum of the dorsal valve. 
DVR NOMENON 653546 6555 Soop ceos Sear enocosssoacgoobeee Cope danems soso eres bese oSeec daasos 
Fig. 5. View of a rather elongate dorsal valve, enlarged to two diameters. 
STROBHODONTAR GAL VINE. asics isiocenion sels cgee ses cee seen eae)siinieceiscccelsisceseeltre cacecs 
Fig. 6. View of ventral valve. Natural size. 
SaRMPLORMYNCHUS) CHEMUNGENSIOs = nicis-l--\-\-nclsinwieiosieles se scieeacive=clelssa cinco «= scirinceneace 
Fig. 7. View of aspecimen referred to the variety arctostriata. Natural size. 
16. View of a specimen corresponding to the typical forms of the species. Natural size. 
IERODUCRUSESPECIOSUS (ca steele ae am eim sane ae sa aoa oom mine seine elnino a=) wn aa lain n= lee tema 
Fig. 8. View showing the surface ornamentation and form of the ventral valve. Natural 
size. 
PRODGCRUS EN AW AG RT U Ste sear alee olden emiejeomciare es elesle mma ame aimee e emma \e “nial ool 
Fig. 9. Lateral view of a somewhat strongly costate variety, enlarged to two diameters. 
STROPHUGDON DASE UNC GIR RACs elena ease iiseemnee nae mae memeiceeesatem ae eelemiclsicl-iinisin\n=le™ e=ism cin 
Fig. 10. View of ventral valve, showing radiating strie and punctate surface. Natural 
size. 
BTROPHODONTA PERPLANAS << <0 ce aco smcacewalnnce coe so a cnoces on acee ceren=s--=n\==es cones 
Fig. 11. View of a well-preserved ventral valve, with a portion of the outer surface exfoli- 
ated. 
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