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MORPHOLOGY OF TXVKRTEBRATE TYPES 



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m 



The posterior end of the male is strongly 

 curved and provided with two hard 

 bristles called spicula which may be 

 protruded through the anus and which 

 serve as organs of copulation. The 

 male has no external genital opening. 

 Instead, the ejaculatory duct opens into 

 the cloaca. 



Body wall. The body wall consists 

 of a cuticle, subcuticle and a layer of 

 longitudinal muscles. The cuticle is 

 composed of the following eleven lay- 

 ers: (i) Outer membrane, (2) outer 

 cortex layer, (3) inner cortex layer, 

 (4) layer of fibrillas, (5) homogeneous 

 layer, (6) band layer, (7) outer fibrous 

 layer, (8) middle fibrous layer, (Q) inner 

 fibrous layer, (10) basal layer, (n) in- 

 ner membrane. Of these layers the 



FIG. 18. Anchylostoma duodenale; male 

 hookworm, after Schulthess, from Blanchard, 

 Zoologie Medicale. a, buccal capsule; b, oesoph- 

 agus; c, nervous ring; d, excretory pore; 

 e, posterior end of oesophagus; /, cuticle; g. 

 muscular layer; h, anterior end of intestine; /, 

 right cervical gland; k, left cervical gland;/, 

 duct of the left cervical gland; m, intestine; n, 

 testis; o, blind end of testis; p, seminal vesicle; 

 q, ejaculatory duct; r, anterior end of spicule; 

 s, spicules; /, left lateral papilla; u, anal papilla; 

 v, chitinous piece behind the anal glands; w, z, 

 chitinous rays of the caudal bursa. 



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