262 



THE INVERTEBRATA 



three pairs of sperm ducts uniting at a common median genital 

 aperture, and two oviducts with separate genital apertures. 



Dinophilus (Fig. 193 D) with very short flattened body consisting 

 of only five or six segments, a ciliated ventral surface and ciliated ring 



yne-p. 



Fig. 193. Examples of the Archiannelida. A, Nerilla, dorsal view of female. 

 A.' Parapodiumi. B, Saccocirrus, side view of anterior end. C, Histriohdella, 

 dorsal view of male. D, Dinophilus y dorsal view of male. amp. ampulla of ten- 

 tacle (ten.); a.f. anterior foot; ch. bundle of chaetae; cl. clasper; cil.b. bands 

 of cilia ; e. eye ; gen.s. genital segment ;j. jaw ; nep. nephridia ; o. ovary ; od. ovi- 

 duct; p. penis; ph. pharynx; p.f. posterior foot; rm. rectum; st. stomach; 

 v.s. vesicula seminalis; /. eyes; p.p. palp; t. testis. A, B, after Goodrich; C, 

 after Shearer; D, after Harmer. 



in every segment ; without septa, dorsal and ventral mesenteries, and 

 a vascular system; with greatly reduced coelom and longitudinal 

 muscles; five pairs of protonephridia ; separate sexes, male with 



