JUNE 19, 1923 COBB: NOTES ON PARATYLENCHUS 255 
There is a small combined vestibule and spear guide, about as wide as the lip 
region and some ten microns long, more or less visible on account of the refrac- 
tive nature of its elements. This portion of the labial structure has for one of 
its main functions the guidance of the spear when in action. The vestibular 
part is about four microns deep and varies somewhat in diameter according to 
the attitude of the lips and spear. Leading backward from the base of the 
vestibule there is a symmetrical set of outwardly bowed, somewhat flexible, 
rather slender, longitudinal elements constituting the main portion of the spear 
guide. The relatively very robust spear is about twice as long as the base of 
the head is wide. It ends posteriorly in a distinctly three-lobed expansion 
toward one-third as wide as the base of the head, the dorsal lobe being slightly 
farthest back, and sometimes at least presenting a dorso-posterior condyle. 
It is somewhat behind, and in a line with, the axil of the dorsal lobe that the 
dorsal salivary gland empties into the oesophageal lumen. The spear often tapers 
more or less regularly throughout its length; nevertheless there is a distinct 
basal part, comprising about two-fifths of the whole, set off by a minute but 
distinct junction mark, and averaging about one-sixth as wide as the corre- 
sponding portion of the head. At its distal end the spear is exceedingly finely 
pointed. Well developed muscles for the protrusion of the spear are readily 
seen and often lie rather close to the spear,—not forming any very marked 
swelling when at rest. Anteriorly there are s7x of these muscles,—one passing 
to each sector of the labial framework. 
No amphids have been seen. There are no eyespots. 
The oesophagus is tylenchoid and presents a very definite, somewhat pine- 
apple-shaped, non-muscular valveless cardiac swelling, half as wide as the base 
of the neck. The very long, large, rather ob-clavate, median swelling, which is 
two-thirds as wide as the middle of the neck, is set off abruptly behind, but is 
decurrent in front and reaches to, and somewhat includes, the base of the 
onchium; in its posterior part it presents a well-developed, elongated-fusiform, 
triplex valve, occupying one-third of the diameter, to which are attached the 
usual radial muscles for the opening of the valve in the act of swallowing. An 
interesting peculiarity of the median swelling is that the contained robust 
tubular oesophageal lining, which is disposed in a single loop or coil when at rest, 
takes on this attitude without much disturbance to the evenness of the contour of the 
swelling itself, thus showing the “‘clavate swelling” to be a distinctly two-fold 
affair,—partly (posteriorly) muscular, and partly (dorsally throughout) gland- 
ular, and with the two tissues so little connected that the glandular part is 
comparatively separate and responds but little to the movements of the tubu- 
lar lining. Ordinarily one would expect the anterior narrower part of such a 
long median swelling to curve or coil along with the lining. Though the 
limits of the true median bulb (not the clavate swelling but the included 
median bulb more properly speaking), are often somewhat indefinite anteriorly, 
it may properly be described as ellipsoidal, two-thirds as wide as the neck and 
two and one-half times as long as wide; in other words the entity of the median 
muscular bulb is not entirely lost. Behind the pharynx the oesophagus is one- 
sixth, at the nerve ring only about one-tenth, in front of the cardiac swelling 
about one-eighth, and finally one-half, as wide as the corresponding portion of 
the neck. The lining of the oesophagus is tubular and narrow, and distinct 
except in the posterior glandular bulb,—most distinct in the clavate swelling. 
There are well developed salivary glands. ‘The nucleus of one of these organs 
may be seen in the dorsal sector of the cardiac swelling, as already described,— 
dorsad and occupying the major part of it,—and emptying into the oesoph- 
ageal lumen near the onchium. It is doubtful if salivary secretion passes 
also into the base of the fusiform median valve, though there seem to be two 
subordinate nuclei in the cardiac swelling. 
