Cobb — Nematodes, mostly Australian and Fijian. 



53 



Genus APHELENCHUS, Bastian. 



Transparent striated round worms, nearly always totally devoid of bristles or 

 setse, varying in length from one-half a millimetre to one and a-half millimetres, 

 attacking the tissues of plants by means of a spear and sucking apparatus of the 

 following construction : a more or less distinctly three-bulbed spear, capable of being 

 thrust forth and withdrawn by appropriate muscles, is connected with a powerful 

 oesophageal sucking-bulb, by means of a tube whose lining is more chitinous than 

 is usual in most Nematode genera. Behind the median bulb, the oesophagus 

 continues for a short distance as a narrow tube, but soon gradually enlarges and joins 

 the intestine in such a manner that it is often impossible to say where the oesophagus 

 leaves off and the intestine begins. The oblique nerve-ring is situated just behind 

 the sucking-bulb. 



1. A. microlaimus, Cobb, 

 seven hundred transverse strise. 



■7 1-3 1-7 



— ^ -7 mm. The cuticula is traversed by 

 To the slightly convex-conoid neck succeeds a some- 

 what rounded head with six minute rudimentary lips, which are to be seen only in 

 certain oblique aspects, and which are destitute of papillae. The pharynx is armed with 



an unusually short spear, whose base presents 

 three rudimentary bulbs. The oesophagus is 

 one-fourth as wide as the neck and terminates 

 posteriorly in an ellipsoidal bulb four-fifths as 

 wide as the base of the neck ; thence the ali- 

 mentary canal continues, at first narrow, but 

 gradually widening. The bulb is, morphologi- 

 cally, probably the median bulb — the posterior 

 part of the oesophagus being rudimentary and 

 indistinguishable from the intestine. Nerve- 

 fibres appear to exist both behind and in front 

 of the bulb. The rectum seems to be about 

 equal in length to the anal body-diameter. The 

 ventral excretory pore is situated at a distance 

 behind the oesophageal bulb equal to twice the 

 length of the latter organ ; the gland of which 

 IV, posterior it is the outlct is a very long and narrow cell 

 as far behind the excretory pore as the latter 

 is behind the mouth. The tail is conical to the terminus, which forms an outlet 

 Yor the secretions of the caudal glands. The posterior branch of the sexual organs 

 is only half as long as the anterior, and is therefore somewhat rudimentary. 



The ventrally- arcuate conoid tail of the male presents a 



a, lips. 

 6, spear. 



c, nerve-ring (?). 



d, median (sucking) bulb. 



e, ventral excretory pore. 



f, ventral gland. 



g, blind end of testicle. 

 h, intestine, 



i, cuticle. 



j, spermatozoa. 



h, spiculum. 



I, chitinous accessory part. 



m, anus. 



■«, ventral papilla. 



u, terminus. 



Fig. 10. — Aphdenchus microlaimus. 

 I, male worm. II, head of the same, 

 portion of the middle of the body, 

 extremity. 



Ill, 



■9 1 10-5 



-M' 



,68 



95-1 



■8 1-3 1-7 2-4 1-7 



