Geroulb. — Caudina. 
PLATE 4. 
Abbreviations. 
amp. 
Ampulla of tentacle. 
mu. tr. 
Transverse interradial 
ann. n. 
Nerve ring. 
muscles. 
aq. crc. 
Circular water canal. 
n. buc. 
Buccal nerve. 
aq. r. 
Eadial water canal. 
n. con. 
Conical buccal nerve (ab¬ 
clc. 
Cloaca. 
normality). 
dt. gen. 
Genital duct. 
n. r. dx-d. 
Eight-dorsal radial nerve. 
e'n. crc. 
Circular epineural canal. 
n. r. ex. 
External band of same. 
e’n. r. 
Eadial epineural canal. 
n. r. i. 
Internal band of same. 
en’th. 
Endothelium. 
n. ta. 
Nerve of tentacle. 
e’th. hue. 
Epithelium of the buccal 
o. rsp. dx. 
Eight branch of respira¬ 
region. 
tory tree. 
hpn. r. 
Hyponeural canal. 
o. rsp. s-d. 
Left-dorsal branch of res¬ 
mad. 
Madreporic body. 
piratory tree. 
mu. Ig. 
Longitudinal radial mus¬ 
o. rsp. s-v. 
Left-ventral branch of 
cles of body-wall. 
respiratory tree. 
mu. Ig.’ 
Longitudinal muscles in 
pa. an. 
Anal papilla. 
the wall between aq. r t 
pa. gen. 
Genital papilla. 
and h’pn. r. 
spht. buc. 
Buccal sphincter. 
mu. r. buc. 
Eadial muscles of buccal 
va. sng. 
Antimesenterial blood 
region. 
vessel of the small in¬ 
mu. ta. 
Muscle layer of tentacles. 
testine. 
Fig. 43. Cross section of the radial nerve, showing distribution of fibers from 
its inner band. X 270. 
Fig. 44. Eadial longitudinal section through the buccal region and the wall of 
the tentacle. X 118. 
Fig. 45. Section nearly parallel to the plane of the nerve ring and the right- 
dorsal radial nerve at its beginning. The section is viewed from 
behind and shows on the right the origin of the abnormal buccal 
nerve cone. X 440. 
Fig. 46. General anatomy of a specimen opened along the right side of the 
dorsal interradius. Natural size. 
Fig. 47. Section parallel to that shown in Fig. 45, but further forward. This 
shows the abnormal nerve cone in cross section. X 118. 
Fig. 48. Sections parallel to the plane of the nerve ring, showing the origin of 
a tentacular nerve. X 50. 
Fig. 49. Cross section of a buccal nerve trunk close to the axial side of the 
nerve ring. X 370. Compare Fig. 44. 
Fig. 50. Eadial longitudinal section showing the posterior termination of the 
radial nerve, the anal papilla (terminal tentacle of the water- 
vascular system), etc. X 280. 
