THE HAIR-WORMS. 129 
The second suborder, Gordiacea or hair-worms, differ in 
their mode of development from the true Nematode worms, 
the embryo of Gordius being armed with oval spines, thus 
Fig. 89.—Gordius aquaticus. A, egg; B, egg undergoing segmentation of the 
yolk; C, embryo es with the primitive stomach, an infold_of the -outer ger- 
minal layer of cells (ectoderm); D. embryo farther advanced ; E, !urva, with the 
three circles of spines retracted within the cso hagus; F, the same stage greatly 
enlarged to show the internal organs; c, middle circle of spines, the head bei: 
retracted ; 72, muscular layei (7); z beak or proboscis; é, intestine ; z, 2, embryonal) 
cells; /, excretory tube leading from g, the secretory glands; @, esophagus; 2, rec- 
tum; 7, anus, «the second larva, encysted in a fish—(after Villot). » Gordius 
varius, end of body of male, much enlarged. 1, Gordius aguaticus, end of body 
of male, much enlarged. K, Gordius aguaticus, natural size.—(H, 1, K, drawn from 
nature by J. S. Kingsley.) 
reminding us in this respect of Achinorhynchi, but the em- 
bryos, larve and adult have a well-developed alimentary 
canal. ; 
