No. 414.] MORTH-AMERICAN INVERTEBRATES. 481 
miliary granules, or somewhat larger straight or curved rods, 
which are often widened and perforated at the end. These 
rods are almost invariably present in the pedicels, papilla, and 
tentacles, and are then known as supporting rods. In other 
parts of the body wall they often are more or less irregularly 
and profusely branched and then form rosettes (Fig. 26). 
Sometimes the deposits are flat, thin, and wide, and are called 
plates, which may be perforated with smooth-edged holes 
(Fig. 19), or the holes may have teeth on the edges (Fig. 13). 
If a perforated plate has a projection rising perpendicularly from 
the middle, made up of several rods more or less joined together, 
it is called a able (Figs. 15-17, 23-25); the perforated plate 
being called the disk and the projection the spire. Sometimes 
tables occur with the disk reduced or wholly wanting, and 
sometimes the spire is greatly reduced. Very often the per- 
forated plates are oval or elliptical in shape, with the perfora- 
tions regularly arranged in pairs, and they are then called 
buttons (Fig. 27); these may be smooth, knobbed, or spiny. 
Quite often the calcareous particles assume the shape of some 
familiar object, from which they receive names; as anchors 
(Fig. 12), wheels (Fig. 14), cups (Figs. 20-22), etc. In a few 
species these calcareous deposits seem to be wholly wanting ; 
In some they are confined to special regions of the body ; in 
many, two or more different kinds are found, usually in 
Separate layers of the body wall; and in a few they are so 
abundant, or so large and close together, as to make the body 
wall stiff, and sometimes firm, or even rigid. Beside these 
colorless calcareous deposits, we find in a few genera (Trocho- 
stoma and its allies) reddish-brown or claret-colored concretions 
(Fig. 18), which are often so abundant as to give their color to 
the whole animal, or at least to large spots and patches. In 
Such species the calcareous deposits themselves are often 
iota tinged with the same coloring matter as the concretions, 
un! they are free from it. In a few genera prominent 
Bias ` bits of lime, usually five in. number, are grouped 
e anus. These are called anal teeth. 
— the cesophagus is a ring made up of plates of lime, 
as the calcareous ring. There are usually ten of these 
