HELIX — GLANDULAK AND MrSCULAR SYSTEMS. 
1.5S 
The Lymphatic glands are not strictly localized in onr type ; the 
phagocytic or lyni])h cells being diffused amongst the connective 
tissue in various parts of the body, although the function is most 
actively carried on within the respiratory plexus in which the lym- 
phatic cells thickly surround the larger pulmonary vessels. 
The Xephridium kidney) or renal organ (see p. 146, f. 306), 
an important secretoiy and the chief excretory organ, is of an ochreons- 
yellow colour, and placed in the rear of the pallial cavity, between the 
rectum and the pericardium. It communicates with the latter by a 
ciliated canal, the reno-pericardial funnel, and with the exterior by a 
thin-walled duct or ureter, which arises at the proximal end of the 
kidney and runs along its right side to the distal end, returning along 
the right side of the mantle cavity above the rectum to the pulmonary 
orifice, the last tract forming the so-called secondary ureter. 
'I’he organ is of a parenchymatous and vascular character, with 
its internal walls thrown into a number of lamellar folds, projecting 
within the lumen or cavity, and is permeated by an intricate j)lexus of 
vessels through which venous lilood, somewhat intermingled with 
arterial, circulates before reaching the auricle : its glandular secretory 
ei)ithelium, which contains rounded granules or concretions, eliminates 
from the blood the uric acid and other substances, which are expelled 
from the system by the ureter. 
The IMrscuLAR .system is very complicated, and its constituent parts 
too numerous to be individually particularized. The principal, how- 
FiCi. 321. — Disfiection showing the general muscular system of Helix aspersa and the arrange- 
ment of the extrinsic muscles of the huccal bulb (after Howes). 
i>J'. buccal bulb ; h.c. constrictor muscles of bficcal bulb ; c.i/i. columellar muscle ; eij/i. depressor 
muscles of buccal bulb ; /. foot ; levator muscles of buccal bulb ; o. ommatophore ; o’, oeso- 
phagus ; buccal protractor muscles; pharyngeal or buccal retractor ; r.s. radular sac ; 
s.d. salivary ducts ; t. anterior tentacle. 
ever, are the retractors of the foot, those of the huccal mass and 
neighbouring organs, the penial retractor, the constrictor muscles of 
the mantle margin and of the pulmonary aperture. Of a subsidiary 
