On Trish Spectes of Kylais. 505 
striction 3°8; mastoid breadth 11°6 ; front of canine to back 
of m*® 7:5; front of lower canine to back of m; 8°5. 
Hab. Mangala, N. of Gondokoro. 
Type. Adult male. B.M. no. 2. 7. 4.3. Collected and 
presented by W. L. 8. Loat, Esq. 
I cannot find any known species to which this Nyctinomus 
can be assigned. None of Heuglin’s show any relation to it, 
even apart from the peculiar gland above described, which he 
might have overlooked. It is curious that the two Mangala 
species should each be distinguished by a glandular structure 
unique of its kind, 
L.—WNotes on Irish Species of EBylais. 
By J. N. HABert. 
Previous to the publication of Dr. Koenike’s paper on 
Lylais * in 1897 only a single species—L. extendens, Miiller 
—was recognized by zoologists ; but it was apparent that the 
genus contained many type forms differing from one another 
quite as much as those of Hydrachna. Several papers on 
ylais have since been published, containing descriptions of 
new species, so that the genus now promises to outnumber in 
species most genera of water-mites. 
Many of the large red mites which may be commonly 
found during the summer months amongst plants growing in 
stagnant or slowly flowing water are referable to species of 
Eylais. In size they are the giants of the Hydrachnide, 
often reaching 5 or 6 millimetres in length. 
Perhaps the most notable characteristics of this genus are, 
in the first place, the structure of the eye-plates, the four 
lenses of which are grouped together on a chitinous plate 
placed anteriorly in the middle line of the body, and the 
peculiar way in which these mites swim. Only the first three 
pairs of legs are then brought into play; the fourth pair, 
being without the long swimming-hairs, are trailed in an 
extended position, rather suggestive of a pair of rudders, 
while the animal swims. 
The species of Hylats are very similar in general shape. 
The specific characters are founded on the comparative 
structure of the bard chitinous parts of the body, especially 
of the eye-plates, mouth-organs, and palps. All of these 
characters vary more or less in the same species, so that it is 
* 1897, Koenike, “Zur Systematik der Gattung Lylais, Latreille,” 
Abh. Ver. Bremen, Bd. xiv. pp. 279-295, 
