GEROULD. — Caudina. 
PLATE 6. 
Abbreviations. 
aq. r. 
Radial water canal. 
mu. Ig. 
Longitudinal muscle fi¬ 
cl. fol. 
Follicular cell. 
bers of body-wall. 
e'n. r. 
Radial epineural canal. 
mu. Ig.' 
Longitudinal muscle fi¬ 
e'th. ex. 
External epithelium of 
bers of rudimentary 
Polian vesicle. 
ambulacral foot. 
e'th. ex. oa. 
External epithelium of 
mu. tr. 
Transverse muscles of 
the ovary. 
n. 
Nerve. [body-wall. 
e'th. i. 
Internal epithelium* 
par. oa. 
Wall of the ovary. 
hp'n. r. 
Hyponeural canal. 
tis. con't. 
Connective tissue. 
lac. oa. 
Lacunar blood vessel of 
vt. ex. 
External layer of yolk. 
m'py. 
Micropyle. [the ovary. 
vt. i. 
Internal layer of yolk. 
mu. crc. 
Circular muscle fibers. 
z. r. 
Zona radiata. 
Fig. 73. Cross section of the stone canal. X 12. 
Fig. 74. Section of the madreporic body, nearly perpendicular to its flat sur¬ 
faces. X 37. 
Fig. 75. Longitudinal section through the wall of the Polian vesicle. X 535. 
Fig. 76. Cross section through the wall of the circular water canal. X 535. 
Fig. 77. Longitudinal section through a tentacular canal and upper part of 
radial plate, showing the valve of the tentacle. X 280. 
Fig. 78. Diagrammatic radial section through a tentacle showing the circula¬ 
tion of fluid in it. 
Fig. 79. Cross section through the posterior end of a radial water tube and its 
lateral vessels (rudimentary ambulacral feet) along the line AB of 
Fig. 80. X 280. 
Fig. 80. Graphic reconstruction of the terminal tentacle (the anal papilla) and 
the two rudimentary ambulacral feet. Scale 6f p, to 1 mm., or 
X 150. 
Fig. 81. Peritoneal epithelium from the wall of the ovary. Maceration prepa¬ 
ration. X 240. 
Fig. 82. The same. Silver-nitrate preparation, x 240. 
Fig. 83. Part of a cross section of wall of ovary of a young individual. X 720. 
Fig. 84. Muscle fiber from the wall of the ovary. X 205. 
Fig. 85. Follicular epithelium. Silver-nitrate. X 240. 
Fig. 86. Part of cross section of wall of ovary of Cucumaria frondosa. X 240. 
Fig. 87. Young ovum. X 235. 
Figs. 88,89. Slightly older stages in the growth of the ovum. X 235. 
Fig. 90. Ovum showing deep staining of a superficial layer, preparatory to 
formation, of a zonaradiata. X 235. 
Fig. 91. Ovum showing two layers of yolk separated by intravitelline mem¬ 
brane. X 235. 
Fig. 92. Surface view of interior of ovary showing a well-grown ovum in posi¬ 
tion and the micropyle projected on the germinative vesicle. X 226. 
Fig. 93. Section of a nearly full-grown ovum. Fol’s chromic-osmic-acetic 
mixture. Ehrlich’s haematoxylin and eosin. X 235. 
