XV1. ARTIFICIAL KEY TO THE 
Shell depressed, or ear-shaped. 
Shell entire 
Shell perforated 
2. Shell irregulary spiral, or irregular. 
(g-) 
aah holes - . - 
Aperture rounded, entire - - - 
Tube with a longitudinal slit - - - 
3. Shell flat, or simply conical, not spiral. 
Conical, curved - - - - - 
Anterior margin notched, or the apex perforated 
Conical or depressed - - - - 
Conical or depressed - - - 
Conical or depressed, muscular impression divided b 
a groove- - - - - 
My 
Conical or depressed, muscular impression divided by 
a groove - - : - 
Shell small, translucent, trigonal - - 
4. Shell multivalve. 
Shell composed of eight transverse valves - 
Lamellibranchiata. 
1. Two adductor impressions, nearly equal. 
(a.) Pallial line sinuated. 
* Ligament none. 
Hinge with accessory plates - - - 
** Ligament external. 
Equivalve, thick, gaping - - - 
Compressed, thin, ligament anterior - - 
Three diverging cardinal teeth in each valve 
«** Ligament internal. 
Small, thick, produced behind - - 
Thin, cartilage with a free ossicle — - - 
Ligament in a triangular pit, two candinal teeth 
Ligament in a triangular pit ; one cardinal tooth 
(b.) Pallial line simple. 
* Ligament external. 
Radiately ribbed - 2 3 2 
Thin, no epidermis — - - : é 
Covered with a long epidermis - - 
* Ligament internal. 
Thin ; one or two cardinals and laterals 
Thick ; two anterior laterals in each valve - 
Hinge with many teeth in a line ; not pearly inside - ArcIDm 
Hinge with many teeth in a line ; pearly inside 
2. Two adductor impressions, very unequal ; 
Shell closed - - - = Z 
Shell gaping - - - = = 
3. One adductor impression. 
Shell eared - - - - - 
Shell eared, gaping — - - - - 
Shell irregular, lower valve with a hole or notch 
Shell irregular, no hole nor notch - - 
MARINE SHELLS. ° 
Page 
LAMELLARIIDEH 59 
HALIOTID 104 
VERMETID® 84 
SILIQUARIIDH 805 
CAPULIDE 87 
FISSURELLID& 105 
ACMBADE 88 
PATELLID 107 
SIPHONARTIDH 35 
GADINIIDE 36 
APLYSIID 123 
CHITONIDE 110 
PHOLODIDE 132 
GLYCINERIDH 134 
"TELLINIDE 141 
VENERIDE 146 
CoRBULIDE 135 
ANATINID 135 
umbones anterior. 
MACTRIE © 138 
PAPHIID® 145 
CARDIII 2 15: 
LUCINID® 155 
SOLEMYID 157 
LASELD 156 
ASTARTIDB 158 
162 
NvucuLipa& 163 
My tnir 2a 166 
AVICULIP 28 169 
PECTINID 28 170 
VADULID 2 Wiz 
ANOMIIT 
OSTREIL 2 
