b GLOSSARY. 



Retiise, when the lower whirls are pressed into the body. 

 Rostrum, see Beak. 

 Rugose, wrinkled. 



Scabrous, rough. 



Serrated, toothed like a saw. 



Semilunar, like a half-moon. 



Sessile, low, dwarf. 



Sinuous, waved. 



Sinus, a deep cut, as in the lip of the Murex Babylonius. 



Siphon, a prolonged tube running through the partitions 

 of chambered shells. 



Slope, the side from the beaks. 



Spinous, having prickles or thorns. 



Spire, is formed by the whole of the upper whirls. 



StriiB, lines flat, or slightly raised : they are called longi- 

 tudinal, when they run from hinge to margin; trans- 

 verse, when in a contrary direction ; and concentric, when 

 they form segments of circles. 



Suhcordate, approaching the form of a heart. 



Suhpellucid, not quite clear. 



Subulate, tapering. 



Superior, see Margin. 



Suture, a toothed joint. 



Teeth, (in Univalves), angular plaits, as on the pillar lip 

 of Volutes: (in Bivalves), pointed protuberances with- 

 in the hinge, by which the valves are united. They 

 are called: alternate, when the teeth of one valve are 

 received between the teeth of the other valve ; articu- 

 lated, when the tooth is received into a corresponding 

 cavity in the opposite valve ; cardinal, the central tooth 

 or teeth of the hinge; compressed, when flattened; erect, 

 perpendicular to the plane of the hinge ; forked, having 



