386 Animal Biology 



muscular, sucking pharynx. Muscles attached to the outside of the 

 pharynx contract and expand it to cause suction. A narrow esophagus 

 connects the pharynx with the large, thin-walled crop which is used for 

 storage. Posterior to the crop is the thick, muscular gizzard for grinding 

 by means of grains of sand and similar materials. The gizzard leads to 

 the long intestine, with its deep, dorsal fold, the typhlosole (tif'losole) 

 (Gr. typhlos, blind; solen, channel). The latter increases the absorbing 

 surface of the intestine and is filled with chlorogen cells (klo-rog' o jen) 

 (Gr. chloros, greenish-yellow) which probably aid in digestion of foods 

 and elimination of wastes. The anus is at the posterior end of the earth- 

 worm. 



•Dorsal vessel 



eart intestino-tegumentary 

 — vessel 

 -Ventral vessel 



Heart 



■ y =f Sub-neural vessel 



'!Sw.,iiiSaBa;:iJ^ T^'Ci^iaitJlEailc^iatx 



X SepU j^ IX Septa 



Septa 



Dorsal ve ssel intestino-tegumentary 



vessel 



CEsophagiis 



VIII 

 Dorsal vessel 



Ventral vessel 

 Sub-neural vessel 



Nephridium 

 Lateral-neural vessel 



Parietal 

 ve«sel 



i^ Typhlosolar 

 vessel 



Ventral 

 vessel 



Efferent intestinal vessel 



T-v ^Sub-neural vessel 



Afferent intestinal vessel 



Dorsal vessel 



Typhlosolar vessel 



-'Ventral vessel 

 Sub-neural vessel 



Parietal vessel 



Fig. 186. — Earthworm circulatory system (somewhat diagrammatic). A, Longi- 

 tudinal view in segments VIII, IX, and X; B, cross section of same region; C, 

 longitudinal view in region of intestine; D, cross section of same region. (From 

 Hegner: College Zoology. By permission of The Macmillan Company, publishers.) 



Three pairs of calciferous glands (kal -sif e rus) (L. calx, lime; ferro, 

 to carry) near the esophagus secrete calcium carbonate (lime) into it to 

 neutralize acid foods as well as to line the tunnels (burrows) through 



