MK. J. N. HALBERT : NOTES ON ACARI. 363 
Notes on Acari, with Descriptions of New Species. By J. N. Halbbkt, 
BI.R.I.A. (C!ommimicated by Dr. W. T. Calman, F.R.S., Sec.L.S.) 
(Plates 20-22.) 
[Bead 1st March, 1923.] 
With a few exceptions the Acari recorded in the following paper were 
collected in Ireland since the publication of the Clare Island Survey reports 
seven years ago. The list of Acari there recorded (23) was p^-actically a 
complete one in so far as the Irish terrestrial forms were then known. A few 
years later an account was given of the species found living in the zones of 
the sea-shore affected by the tides (34). At the present time, collections are 
being made with the intention of preparing a more complete list of our 
Acarid fauna, but much remains to be done in this respect. Meanwhile it 
is desirable to record a certain number of new and interesting forms as a 
contribution to our knowledge of the Acari in these islands. 
The literature dealing with the Acari is very considerable ; large numbers 
of species have been described by European workers in recent years, and, as 
very many of these species are unfigured, the diflficulties of identification are 
greatly increased. In the present paper short descriptions only are given, 
and such figures as seem necessary in a group where the details of structure 
are so varied and often of so comparative a character. In all, some sixty-eight 
species are recorded ; sixteen of these, and also a few varieties, belonging 
to the families (lamasidse, Oribatidse and Trombidiidse, are apparentlj- 
undescribed. Including these new forms, about forty species are now 
recorded for the first time from the Britannic area. The types of two of the 
new species, in Lasioseius, were collected by Mr. A. D. Michael on the coast 
of Cornwall some years ago. 
I am indebted to a few friends for assistance in the collecting of specimens, 
more particularly to my colleague, Mr. A. W. Stelfox ; the discovery of some 
of the more interesting forms is due to him. I have also to thank 
Dr. A. Berlese for kind help in the identification of some of the species : 
others are recorded on my own responsibility. The type-specimens of all 
the new species are in the collection of the Irish National Museum. 
Gamasus (Eugamasus) crassitarsis, sp. nov. (PI. 20. figs. 1 a-c.) 
Male. A large robust species measuring 1600 /j, in length ; general 
characters as in the subgenus Eugamasus, to which the species belongs. 
Shoulders well marked ; hairs long, those on the second dorsal shield 
numerous and somewhat adpressed. Sternal region of ventral plate with 
faint scale-like markings on its anterior half, concave at the centre of the 
