THE MUSSEL. 



63 



PLATES XV., XVI. 



THE MUSSEL. 



a. Anus. 



a.a. Anterior adductor muscle.* 



a.a'. Nerve to the same. 



a.ao. Anterior aorta. 



a/. Albuminous fluid. 



a.m. Adductor muscle. 



a./). Posterior adductor muscle.* 



a.p'. Nerve to the same. 



au'. Right auricle. 



ait". Left auricle. 



b.d. Bile-duct. 



b.d'. Aperture of bile-duct. 



b.n. Branchial nerve. 



l>r. Branchiie. 



br.<i. Afferent branchial vessel. 



br.a'. Afferent branchial trunk. 



br.e. Efferent branchial vesse'. 



br.e'. Efferent branchial trunk. 



br.l'. Left outer gill lamina. 



Irr.l". Left inner gill lamina. 



Inj. Byssus. 



bif. Byssus gland. 



c.c. Supraocsophageal commissure. 



c.ij. Cerebral ganglion. 



e.p. Cerebro-pedal commissure. 



<./'.. Cerebro-splanchoic commissure. 



e.s. Exhalent siphon. 



/. Foot. 



ij.a. Genital aperture. 



;/.''. Genital duct. 



ij.ijl. Genital gland. 



</.*. Germinal spots. 



(/.c. Germinal vesicle. 



i. Intestine. 



i.b.c. Infrabranchial chamber. 



/... Inhalent siphon. 



kb. Keber's organ. 



/:/. Ligament. 



Iji. Labial palps. 



lp'. Artery to the same. 



//'". Nerve to the same. 



Iv. "Liver." 



in. Month. 



me. Micropyle. 



na. Nacreous layer. 



nc. Nucleus. 



<e. (Esophagus. 



l>.a'. Right anterior pallial artery. 



p.a'. Left posterior pallial artery. 



ji.no. Posterior aorta. 



p.ao'. Posterior aorta of right side. 



p.ao' 1 . Posterior aorta of left side. 



lie. Pericardium. 



/"I. Pedal ganglion. 



pd.a. Pedal branch of anterior aorta. 



/it. Cells of embryonic mantle. 



]>l '. Right pallial lobe. 



ji.in. Pallial muscle.* 



ji.n. Pallial nerve. 



]>o. Periostracum. 



p.p. Protractor pedis muscle.* 



/;/. Prismatic layer. 



p.s. So-called parieto-splanchnic ganglia. 



l>.r. Efferent pallial vessels. 



r. Rectum. 



r'. Its cut edge. 



re. Glandular portion of excretory organ. 



re'. Nonglandular vestibule of excretory organ. 



re". Renal aperture (or style passed into the 



same). 



re.c. Interrenal aperture. 



re.ji. Reno-pericardial aperture. 



r.m'. Anterior retractor muscle. 



r.m". Posterior retractor muscle.* 



r.m'''. Lesser retractor muscle.* 

 r.v. ' Afferent renal vessel. 



r.v'. Efferent renal vessel. 



*. Valves of shell. 



s'. Inturned edge of shell. 



x.l>.<-. Suprabranchial chamber. 



Note. The references marked thus, :;: , refer in Fig. III. to the crests of attachment of these muscles. 



