Monhystera agilis de Man.

Allgén, C. A., 1953, Terrestrial nematodes from Jan Mayen, Annals and Magazine of Natural History 12 (6), pp. 665-688 : 684-685

Monhystera agilis de Man. (Fig. 10.)

de Man, 1884, pp. 43-44, pl. iv, figs. 15, 15 a-d.

Dimensions.-Body-length= 0.851 mm., max. width=0.0 3 3 mm., oesophagus= 0.220 mm., t a i l=0.1 1 5 mm., v u l v a =0.6 1 4 mm., α=25.79, β =3.87, y =7-4, V =72.15 per cent.

The f e,w specimens of a Monhysterid from E6 agree so well with M. agilis t h a t, although no male is at hand, I m u s t regard the m as synonymous with that species. T h e y are easily recognized b y the large cephalic bristles, the small fine hairs on the whole body, and tile shape o f the head and the tail.

The b o d y o f the Jan Mayen specimens, which is t h i c k e s t in front of the vulva, tapers towards both extremities gradually a n d is provided with sporadic, v e r y fine, submedian hairs.

Cuticle smooth. The head is truncate to rounded. A t the front e n d there are some short bristles. Behind these the head is provided with two lateral solitary bristles a n d four submedian pairs of bristles, the anterior of which pair is 1/3 shorter t h a n the posterior ones, whose length is equal to the corresponding head -diameter at their level.

The buccal cavity is large, about twice as broad as deep.

Lateral organs situated 15µ behind the front end, rounded, very small, measuring in section only 2 µ, i.e. 1/9 of the corresponding head-diameter.

The oesophagus is o f a b o u t even thickness, posteriorly built u p o f coarse bundles o f muscles.

The tail is v e r y similar t o t h a t of M. filiformis , elongated, a t first gradually tapering, in the posterior p a r t thinner a n d w i t h a small end tip.

Vulva v e r y far back, a t the e n d o f the third q u a r t e r of the length o f the body. The distance from the anus (0.122 mm.) is a little more t h a n the length o f the tail (0-115 ram.).

Immediately in front o f the vulva the r e is a single shell-egg with the dimensions: 77µ × 31/z.