Mermis Parasitic on Ants of the Genus Lasius. 



369 



cuticular tulie, which can be traced back alongside of the fat-body 

 for a distance of 12*5 mm. (more than a quarter of the length of 

 the worm), at which point it appears to end blindly. The outside 

 diameter of the tube is about 0-0125 mm. Close to the mouth 

 there is a slight thickening of the walls of the tube. The nerve- 

 ring is massive, and surrounds the oesophagus at ■ 57 mm. from 

 the anterior end. 



The vulva, in the form of a transverse slit, is situated a little 

 behind the middle of the body (at 21 mm. from the posterior end 



Fig. 10. — Mermis myrmecophila. Larva from Lasius alienus ; transverse 



section through the body, 

 c, cuticle ; d., dorsal field ; /., globules contained in the "fat-body"; 

 I., lateral field ; m., muscles ; sc, subcuticular layer ; sv., subventral 

 field ; t., testis ; v., ventral field. 



in a specimen 48 mm. long). The distal portion of the vagina, or 

 " vestibule" (fig. 11, ve.) consists of an invagination of the cuticle, 

 running slightly in the direction of the head. After passing 

 through the ventral longitudinal field it becomes a narrow duct 

 (" ovejector ") with thick muscular walls (fig. 11, o.). This describes 

 an S-shaped curve, and gives off at right angles to itself the two 

 directly opposed uteri. The uteri proper are very short (each not 

 more than 1 • 6 mm. long) and somewdiat club-shaped, expanding 

 gradually in diameter on passing further away from the vagina. 



