180 
ANODONTA — MXTSCULAR SYSTEM. 
renal organs. Tliej" luive a rich sanguine irrigation mainly by the 
arterial blood returning to the auricles from the mantle lobes and 
outer gills, from -which the 
glands eliminate a still more 
acrid secretion than that of the 
nephridia, which is probably 
dischai’ged into the pericardium 
and passes outwards by way of 
the reno-pericardial orifice and 
the ureter. 
The Ijymphatic (Tlands are, as 
in Hell.r, diffused amongst the 
connective tissue in almost all 
parts of the body, hut although 
the function is more especially 
concentrated within the gills, 
it is not localized, and does not form a definite organ as in some of 
the Oiusthohranclis. 
The ]\Iuscui.AU system of Anodnnta, so far as relates to the larger 
and more e.xtrinsic muscles, may l)e termed Pedal or Pallial, according 
to the area witli which they are most closely identified ; there are, 
U.T 
Fid, 35(). — Longitudinal section through the 
right accessory pericardial space of Anoiionta 
cyf^nea to show tlie openings of the pericardial 
gland and the reno-pericardial funnel and neigh- 
bouring organs X 3 (after Orohhen). 
right genital duct : X*. anterior end of kidney 
in section, sliowing its glandular structure and the 
more dorsally placed ureter ; t?. openings of peri- 
cardial gland into the accessory space ; />.c. peri- 
cardium ; A'-i'’/. pericardial gland ; r. rectum ; 
7 \/. reno-pericardial funnel. 
Fig, 3.)1. — The left valve of an Anodonta cygnca from Clumber Lake, Notts., collected by 
.Mr. C. T. Musson, F.L.S., showing the muscular scars, which indicate the places of attachment 
of the extrinsic muscles. 
a. ad. anterior adductor scar ; a./>. anterior pedal protractor scar, the abdominal retentor scar of 
Clessin ; a.r. anterior pedal retractor scar ; /.ad. posterior adductor scar ; /./. pallial line ; /.r. 
posterior pedal retractor scar ; n.r. umhonal retentor or pedal levator scars. 
liowever, innumeralxle smaller, though intrinsic muscles beneath and 
intimately connected with the general integument, while the walls of 
