PLATE XXXI. 
Figs. 1, la, lb, 1 c, Id. — Thuiaria pharmacopola (p. 66). 
Fig. 1. — A colony ; natural size. 
Fig. la . — A portion of main stem, near its distal end, with a pinna; magnified 15 
diameters. One gonangium is present on the pinna and the points from 
which others have fallen are seen between some of the pairs of hydrothecse ; 
front view. 
Fig. lb . — Portion of a pinna with three gonangia ; lateral view ; magnified 15 diameters. 
Fig. lc. — Transverse section of the stem towards the base with the ccenosarc removed 
by maceration in caustic potash, showing its cavity consisting of numerous 
longitudinal chambers formed by the coalescence of the thick chitinous 
walls of the tubes which compose the fascicled stem ; magnified about 10 
diameters. 
Fig. Id . — Transverse section of the stem near the distal end, similarly treated, showing 
a single cavity enclosed within the thick chitinous walls of the stem, here 
become monosiphonic ; magnified, about 20 diameters. 
Figs. 2, 2 a. — Thuiaria quadridens (p. 66). 
Fig. 2. — A colony ; natural size. 
Fig. 2a. — Portion of a colony ; magnified 20 diameters. 
