108 GLOSSARY. 
Pectinated. ‘Toothed, like a comb. 
Peristome. The margin of the aperture; the mouth of the 
shell. 
Pillar. ‘The central column which supports the spire. 
Plicate. Folded, or plaited. 
Pulmonary. Relating to the lungs; animals which breathe. 
Reniform. Kidney-shaped. 
Reticulated. Forming a network. 
Retractile. That can be drawn back. Ex., tentacles of snails. 
Reversed. Applied to shells whose spire winds in the con- 
trary way to that which is common. Ex., Physa. 
Revolute. Rolled backward. 
Rostrate. ‘The elongated canal or beak of univalve shells. 
Rostrum. ‘The snout of the animal of univalves. 
Rufous. Reddish-brown. 
Rugose. Wrinkled. 
Scabrous. Rough, harsh, to the feel. 
Sinistral. Shells with the aperture on the left side. 
Spire. This includes all the volutions but the last, which is 
known as the body, or body-whorl. The form of the spire 
may be acute, concave, depressed, discoidal, obtuse, etc. 
Striated. Marked with fine lines ; longitudinal or transverse. 
Sulcated. Deeply furrowed. 
Summit. The apex, or tip of the shell. 
Suture. The joining of the whorls in the spire. It is more 
or less deeply impressed, and varies in its character. 
Teeth. ‘The aperture of the shell is often furnished with pro- 
jections from its inner margin, which are called teeth. 
Ex., Triodopsis. 
Teeth, of molluscous animals. See Tongue. 
Tentacles. ‘The feelers of snails, etc. 
Tongue, of the mollusca, is a horny, strap-shaped organ placed 
within the mouth, and armed with very numerous micro- 
scopic teeth, arranged accurately in rows both transverse 
and longitudinal, to the number, in some species, of many 
thousands. It serves to rasp off their food. 
Transverse. Crosswise. ‘The measure, or width of a shell 
horizontally from right to left. 
