UNIVALVE SHELLS. 
DIVISIONS. 
flatz . . 
not CONCAVE; LON sy . sf oes we Se ee ote gs «ny oe) UMISCOUS. 
spheroid 
straight or almost straight. . 
Symmetrical .... 
volute;with whorls ' 
COHCAVG;: cn s:cu> & teecencs 
volute: <1. apenas 
monoloculat. 22. '. sn.@arched .. .(. seam. 
straight ; in the form 
VEIVslAIP ON m0, ioe coger aes 
entire... . elliptical... 27 8. 
semi-round. .... 
ii(o(riate | ere ee Bees 
angular... «gsi « 
moderate 
conical or spiral; mouth 
Not Symmetrical . . Channeled “oS... 3: Spies ar. heres 
motchedse “si. sae ae 
anivelites-Omeminely HAG ee cco 6 nice -w Sele Oe Getta alee © ak 
ofa. 
adhering 
multilocular, ¢..". . .. 3 ¢partly straight... 426 . 53 
jnot adhering 
Sepiacer. ... 
Nummulacee. . 
Spherulacez.. . 
Orthoceracez. . 
Lituacez. ... 
Spirulacee. . . 
touching. . Ammonacez. . 
penetrating Nautilacee. . . 
...... Argonautacez. . 
sheath. 
shield. 
Carinacex.. . . 
Vaginacee. .. 
Clypeacee. . . 
Megastomata. . 
ie} Ae) 
7 OS SO POS so os) Sar 
. 
. 
Ellipsostomata.. . p. 
Hemicyclostomata. p. 32. 
Cricostomata. . . p. 
Gonyostomata. . . p. 
Syphonostomata.. p. 
Entomostomata. . p. 
Angyostomata.. . p. 41. 
ae. 
33. 
35. 
36. 
38, 
