264 SCLKROSTÜMA STRUTHIONIS. 



The posterior lateral ray (costa posterior externa Schneid. ^)) 

 is rather slender and originates beneath the base of the 

 common stam of the posterior rays ; the middle rays are 

 separated, the anterior being larger than the posterior. 

 The anterior lateral ray (costa anterior externa Schneid.) is 

 short and narrow , not much longer than the half of the 

 middle ray ; two anterior rays , of which the external is so- 

 mewhat longer than the internal. Before the cloacal ope- 

 ning of the male there are two large and several small 

 papillae. Two long, slightly S-like bent spicules, measu- 

 ring 0,87 m.m., with their distal extremity curved knee- 

 like. The caudal extremity of the female terminating in a 

 conical , pointed tail ; a large , papillose elevation before 

 the vulva, situated 0,25 m.m. above the point of the tail. 

 A bifurcated vagina , passing into two parallel uterine ducts , 

 directed forwards and terminating each in a long ovarian 

 coecum , with numerous coils. 



Length of male 17 m.m., breadth 0,42 m.m. 



Length of female 23 m.m., breadth 0,7 m.m. 



The cuticula is furnished with annular grooves , surround- 

 ing the whole body and not interrupted in the lateral 

 lines; they lie on a distance of 0,012 m.m. from each other. 

 About '/s of the length of the oesophagus the cuticula 

 shows on each side in the lateral line a cup-like depres- 

 sion, in which is placed a small spine, resting on a pa- 

 pillose thickening of the hypodermis. Two similar , but 

 much smaller spines are situated near the base of the 

 conical tail of the female. At a short distance behind the 

 anterior extremity of the body, on the place of insertion 

 of the oral papillae, there is a constriction separating an 

 annular wall from the rest of the body. The oral aperture 

 is surrounded by a crown of numerous conical cilia, 

 standing on a broad edge of the anterior opening of the 



1) Schneider, Monogruphie der Nematoden , p. 130. 



N'otes from the Leyden Museum, Vol. VU. 



