PLATE IX. 
Fie. 1.— A dorsal veiw of the pericardial cavity, mantle not removed. 
p. a. Posterior adductor. au. Auricle. 
r. Posterior retractor. v. Ventricle. 
p. m. Mantle. p. Pericardium. 
o. b. Organ of Bojanus. 
Fie, 2.— A dorsal view of the pericardial cavity, mantle removed. 
p. a. Posterior adductor. v.. Ventricle. 
p.r. Posterior retractor. au. Auricle. 
r. Rectum. o. b. Organ of Bojanus. 
p- Pericardial cavity. 
Fie. 3.— The valve leading from the auricle to the ventricle. 
val. -Valve. .- au. Auricle. 
v. Veutricle. 
Fie. 4.— Organ of Bojanus or renal organ. 
p. a. Posterior adductor. o. b. c. Opening leading from the 
r. Rectum. non-glandular sac to the 
a, Anus. branchial chamber. 
p. r. Posterior retractor. n. g. s. Non-glandular sac. 
p. Pericardial cavity. g. s. Glandular sac. 
v. Ventricle: 0. €. Ss. Opening leading from the 
0. p. g. Opening leading from the glandular to the non-glan- 
floor of the pericardium to dular sac. 
glandular sac. au. Auricle. 
Fic. 5.— Floor of the pericardium, showing the 'two openings (o. p. g.) into 
the renal organ. 
. Fic. 6.—Floor of non-glandular sac, showing openings into the glandular 
sac and branchial chamber, and the openings from the glandular 
sac as shown in Fig. 5. 
Fie. 7. Diagram showing more plainly than fig. 4 the passage leading from 
the floor of the pericardium to the branchial chamber. 
Fie. 8.— Showing nerves in place. 
c. g. Cerebral ganglion. p. g. Pedal ganglion. 
c. c. The commissural cord con- pe. c. Commissural cord connect- 
necting the cerebral gang- ing the pedal and cerebral 
lia. ganglia. 
ps. g. Posterior ganglia. a.m.n. Anterior mantle nerve, 
ps. c. Commissural cord ‘connect- g.n. The nerve whose branches 
ing the cerebral and pos- are the nerves of the gills. 
terior ganglia. p- m.n. Posterior mantle nerve. 
