Some Littoral Mites of Millport. 135 
Gamasus (Halolelaps) glabriusculus, Berl. et Trouess. 
2% Gamasus marinus, Brady, A Review of the British Marine Mites, etc., 1875. 
Halolelaps glabriusculus, A. Berlese et Trouessart, Diagnoses d’Acariens nouveaux 
ou peu connus, 1889. 
Zercon marinus, Moniez, Acar, et ins, marins des Cotes Boulonnais,1890, p. 13. 
The writer had frequently noticed a Gamasid mite, on and under stones 
between tide-marks, at Millport, but it was not until July 1912 that he 
secured adults of both sexes in addition to the nymphs which are more 
commonly found. They agreed in detail (Fig. 6: a, female; 0, anterior 
margin of epistome of a male) with Berlese’s diagnosis, as quoted below 
from the Monografia, 1905. Berlese notes (1905, p. 110)— 
“Lives on the sea-shore under seaweed ; fairly frequent in France, Spain 
(and in Britain ?).” 
He refers, p. 111, to Moniez’s mention of it as very common on the 
Fucus which covers the rocks invaded by the sea. Moniez cites Brady (1875) 
who found his Gamasus marinus in the crevices of magnesian limestone rocks, 
between tide-marks, near Sunderland, and (a single example) washed from 
among the roots of alge dredged off the isle of Cumbrae in the Firth of 
Clyde. This would signify that the species could live constantly sub- 
merged. . 
It must be mentioned that Brady (1875) gives the length of his specimens 
as one-twelfth of an inch, which is more than 2mm. The extreme length 
of the specimens seen by Berlese is 950 y, and the average is about 800 p. 
Two females from Millport, now exhibited, measure each approximately 
820» long, 460 broad. The short description given by Brady, and the 
figure of a palp, a mandible, and a labial cornicle of a Gamasid do not seem 
in themselves to justify Moniez’s confident ascription of his example to that 
species. 
Apart, then, from the consideration of the identity of his species, Brady’s 
note is of interest as raising the question whether a Gamasid can live 
constantly submerged by the sea. Upon this the following observations 
may throw some light. 
The mites, identified from Berlese’s description and figures as Gamasus 
(Halolelaps) glabriusculus, are found at Millport under stones covered with 
Chondrus crispus, or with Cladophora rupestris, and having an incrustation 
of Sponges, Polyzoa, Hydroids, minute Annelids and Nematodes, particu- 
larly those stones between half-tide limit and the upper boundary of the 
Laminarian zone. They are active on these stones when just left by the 
tide, but are not found moving about on stones taken from under water 
