THE EARTH-WORM (Lumbnms terrestris) 



External Features. 



1 . Make a drawing of the dorsal surface, of the first forty segments, showing : 



(a) The body, divided by a series of circular furrows into a number of annuli 



corresponding to the segments or somites, the internal divisions of the 

 body. 



(b) The prestomium, a small conical projection at the anterior end of the 



body. Its base intersects the first annulus. 



(c) The clitellurri, a thickened band of glandular tissue, extending over 



segments 32 to 37. 



(d) The dorsal blood-vessel (if visible), beneath the skin along the median 



line. 



(e) The dorsal pores, situated mid-dorsally in the furrows between the seg- 



ments, the first one between segments 10 and. 11. 



2. Make a drawing of the ventral surface, of the first seventeen segments, 

 showing : 



(a) The mouth, on the 1st segment and overarched by the prestomium. 



(b) The eight chaetae or setse, in each segment except the first and the last. 



These setae are arranged in four pairs, a lateral pair and a ventral pair 

 on each side of the median line. 



Prottomiuffl 



,.<)penings of 

 vSpermatheca' 



Prostomium 



Fig. 19. — Earth-worm [Liimbricus terrestris). A. Dorsal 

 View of the first 40 segments ; B. Ventral View of 

 the first 17 segments ; C. Ventral View of the last 6 

 segments ; D. Lateral View of the first 16 segments. 



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