192 WORMS. 



DIAGRAM X. 

 The Leech. 



To the right is shown (after Wliitman) the external morphology ot 

 the leech, the 26 segments, the 102 rings, the openings of the 17 pairs 

 of nephridia, the position of the 10 " eyes,'' of the sensory spots on every 

 fifth ring, the openings of the male and female ducts. 



Sect, is a diagrammatic representation of a cross section ; cut. the 

 cuticle, epid. the epidermis, c. m. the circular muscles, /. m. the longi- 

 tudinal muscles, g. the gut with two side pockets, d. b. v. the dorsal 

 blood-vessel, v. b. v. the ventral blood-vessel enclosing the nerve-cord 

 («.), /. b. V. the lateral blood-vessels, neph. a. nephridium and its 

 bladder, /. a testis and part of the associated duct. 



Gut shows the food-canal with pharynx [ph.'), pouched crop («-.), 

 stomach {st. ), and rectum (r.). 



Above this is the male reproductive system, with nine pairs of testes 

 [T.) connected by a vas deferens, with anterior seminal vesicles (v. s.) 

 and penis (p.). The asterisk indicates the position of the female repro- 

 ductive system. 



The latter is shown on a large scale, av. the ovaries, gl. the gland 

 around the united oviducts, ut. the uterus. To the side is a cocoon con- 

 taining eggs. (After Vogt and Yung.) 



The figure marked T. pi. shows a tooth-plate with marginal teeth. 

 At its inferior corners the associated muscles are shown. (After Vogt 

 and Yung. ) 



