Fig. 1. 
Fig. 2. 
Fie. 3. 
Fig. 4. 
Fig. 5. 
PLATE 11. 
Page. 
IPINNA LAREST 0 Gocou isco eek Os SARS wae a a eae wea sag causes 17 
a. Left side view; reduced to one-half diameter. 
b. Transverse section of the same. 
OSTREA, SOLENISCUB! c= 5coe.-- cle evics coe slot eo cweleisien mene voice ali fovatetererene ctereee 9 
a. Upper valve of small example; natural size. 
b. Portion of the upper valve of another example, showing by the 
lines of growth the gradual change from a rounded to an elon-- 
gate form. 
VOISELLA (BRACHYDONTES) MULTILINIGERA .....----2 e000 scceee eo eco 18 
a. View of left valve; natural size. 
OSTREA ANOMIOIDES.-- 02. 0.2225 22220. co ccwe cereee connce= cers ancwces fe 10 
a. Lower valve; natural size. 
b. Upper valve of another example. 
BARBATIA BARBATULA....-.-.-..--+- esbooaae BS eA ets aa slats ws beeieee 19 
a. Right side view of an imperfect example; natural size. 
i PHARER EA? (PRATT cele suits cies caie's jtciate es clobicuce Maa eleie oa reer BEDS 21 
a. Left side view of an internal cast; natural size. 
b. Dorsal view of the same. 
 TASPODESTHES? AOBSCURATA bone nce een cee cca se eee eo eee eee 30 
a, Side view ; natural size; showing the enveloping callus removed 
but the thin test remaining. 
b. Similar view of another example, showing a portion of the callus 
remaining upon and covering the spire. 
