G. S. Graham-Smith 
513 
and are probably not true parasites of tbe fly. On the other hand on 
several occasions a number were seen on weakly flies, which appeared to 
be dying and scarcely able to move. They were frequently seen, often to 
the number of eight or ten, under the bodies of dead flies, and seemed 
to be devouring them. In examining some of these mites caught on 
Nov. 19 on decaying animal matter, an interesting observation was 
made. Several had larval nematodes adhering to their legs, as many 
as eight worms being sometimes attached to a single leg. Occasionally 
the worms were attached to other parts of the mite. The mode of 
attachment was not clearly ascertained though a triangular mass of 
material staining with haematoxylin was always found on the surface 
of the mite at the point of attachment. The mass is probably secreted 
either by the mite or by the worm. This discovery was made late in 
the season, and no opportunity occurred of ascertaining whether blow¬ 
flies visiting the materials on which the infested mites were living 
became infected with the worms. Other examples of the same species 
of mite, collected from similar situations in the neighbourhood, were not 
thus infested, and the condition seemed to be very local. Dr G. L. 
Boulenger, who very kindly examined the worms, states that they are 
not the larvae of Habronema muscae, and that without rearing the 
adults it is impossible to determine the species. 
On some of the flies examined hypopial nymphs (Fig. 7) belonging 
to the genus Tyroglyphus were found, and the adults of Tyroglyphus siro 
Plate XXIX. Pigs. 1-3, 5-7. Photographs of living specimens of M. domestica ( x2) 
with mites of the genus Holotaspis attached to them. In fig. 1 a single mite is 
attached between the eyes, in fig. 2 two mites, seen as oval grey bodies, on the 
dorsum of the thorax, in fig. 3. three mites on the ventral surface of the abdomen, 
in fig. 5 two mites on the dorsum of the abdomen, in fig. 6 one mite on the anterior 
aspect of the proboscis, and in fig. 7 one mite on the ventral surface of the abdomen. 
Fig. 4. Photograph of a living specimen of C. vomitoria ( x 2) with a nymph of 
Gamasus sp. attached between the bases of the hind legs. 
Fig. 8. Photograph of the dorsal surface of a nymph of Gamasus sp. ( x 15) 
showing five nematodes attached to the leg projecting upwards and some on other 
legs. 
Fig. 9. Photograph of a leg ( x 30) of a nymph of Gamasus sp. with six nematodes 
attached to it. Three are partly coiled, and the others extended. 
Fig. 10. Photograph of a stained and mounted specimen of a leg of Gamasus sp, 
( x 45) with six nematodes attached to it. 
Fig. 11. Photograph of a stained and mounted specimen of a leg of Gamasus sp. 
( x 60) showing a coiled nematode with a dark haematoxylin staining mass at the 
point of attachment, one extended nematode with a similar mass, and a dark mass 
on the edge of the specimen a short distance above the coiled nematode. A nematode 
became detached from this point during manipulation. 
