PHYLUM ANNELIDA 



213 



intestine, and ectodermal rectum. Blood which is sucked from an- 

 other animal receives a ferment from the salivary glarids of the 

 pharynx, which prevents it from coa^lating. It is then stored in 

 the diverticulae of the crop. The animal is capable of ing'esting three 

 times its own weight in blood, and, since several months may elapse 

 before it is all digested, frequent feedings are not necessary. The 



Fig. 112. — Development stages of Polygordius, an archiannelld. A, blastula ; 

 B, gastrula ; C, early trochophore larva ; D, optical section of trochophore larva 

 showing apical plate with eyespot, head kidney ; and preoral band of cilia ; E, 

 trochophore larva with posterior growth region ; F, segmenting larva ; G, advanced 

 larval condition in which the trochophore larva is seen with head, mouth, eye- 

 spots, and tentacles; H, adult worm, showing faint external segmentation. (From 

 Newman, Textbook of General Zoology, published by The Macmillan Company, 

 after Whitman.) 



