140 Proceedings of the Royal Physical Society. 
than at its base. Moreover this extremity bears two bristles much longer 
than the others of the segment. The species would therefore appear to be 
Bdella longicornis (L. 1758), Sig Thor, 1902. 
= Scrrus vulgaris, Hermann (see Sig Thor, 1904). 
= Bb. rubra, Latreille. 
= B. borealis, L. Koch and Neuman, 1883. 
= B, vulgaris, C. Canestrini, Prospetto dell Acarofauna Italiana (1886). 
= B. decipiens, 1. Tragardh, 1902. 
For other synonyms see Sig Thor, 1904. 
For this species Sig Thor gives the following nete :— 
Locality— Abundant, especially littoral, seldom in grass, under stones, 
under pieces of wood, etc. Norway, Siberia, Nova Zembla, Spitzbergen, 
3ehring Is., Jan Mayen, Greenland, Sweden (7), England, France, Germany, 
Austria, Switzerland, Italy, America. 
The species is evidently of wide distribution and not exclusively littoral. 
Molgus littoralis, on the other hand, is stated by Sig Thor (1904) to be only 
littoral. 
In conclusion, the writer offers the above notes mainly as of personal 
observations of some details of the habits and behaviour of four species of 
littoral mites to which he has given some study. These mites belong to 
families of predaceous, terrestrial Acarina, no doubt attracted to the shore 
by the special abundance of food material it offers. This abundance of food 
probably has direct causal relation to the large size attained by two of the 
species (Hugamasus immanis and Molqgus littoralis). 
Halolelaps glabriusculus shows peculiar adaptation’ to a semi-aquatic 
existence in its habit of availing itself of the shelter and the limited air 
supply of rock crevices and of alga roots. In this way it adapts itself to 
the tidal rhythm. 
SUMMARY. 
In regard to the species mentioned, the principal points of interest noted 
above are as follows :— 
Hugamasus immanis. 
(1) Method of feeding. 
Wy) 
Method of cleaning appendages and body. 
Na 
3) Mode of coition, and particularly the clasping function of the 
“stridulatory processes” of the second leg of the male. 
(4) Number of eggs laid. 
(5) Hatching, 
Halolelaps glabriusculus, 
(1) Occurrence. (2) Relation to submergence. 
