ALIMENTARY SYSTEM — FOOD. 
285 
Tlie Dichodroma double ; Spo/xos, a tract or course) com- 
prise those species in which the intestinal tracts have become reduced 
to one forward and one backwardly directed section ; the detorsion the 
viscera has been subjected to having merged together the rectum and 
9 
Fig. 568. — Alimentary tract of Testacella haliotidca Drap., enlarged, exemplifying the section 
Dichodroma. 
the posteriorly directed plectonic tract, this process also uncoiling the 
cephalic artery from its sustaining position around the anterior 
intestinal loop. 
Tlie Pentadroma (Trh'xe, five ; Spopos, a tract) show five tracts or 
courses beyond the stomach and, as in the Triodromous species, 
have the first anterior intestinal loop encircled by the cephalic artery ; 
Fig. 569. — Alimentary tract of Limax iiiaximus L., exemplifying the .section Pentadroma. 
the two additional tracts in Limax maximus and its immediate 
congeners have the additional anterior loop passed around the 
])haryngeal retractor, which being affi.xed to tbe dorsal integument 
holds this loop in its proper position, tlie final backwardly directed 
tract bending in the rear to join the final tract or rectum. 
Fig. 571. 
Fig. 570. — Anterior folds of the intestinal tract of Limax maxltnus L., showing how the coils 
are held in their anterior position. 
/. plecton; r. rectum; a. aorta dividing into v.a. visceral artery and c.a. cephalic artery, the 
latter encircling the first anterior coil ; p.r. pharyngeal retractor, holding the second coil in place. 
Fig. 571. — Side view showing the pharyngeal retractor encircled by the second anterior intestinal 
coil and its attachment to the dorsal integument. 
/. the second anterior coil of the plecton ; p,r, pharyngeal retractor fixed to dorsal integument b. 
The Food of the Pelecy})oda consists chiefly of Infusoria and the 
various floating microscopic organisms brought to them by the cur- 
rents produced by the ciliary investment of the branchim and other 
