Halrert — The Acan'na of the Seashore. 141 



Cephalotliorax iTlatively small ami much narrower than ahdiimcn ; front 

 margin slightly concave, with a small central papilla. There are two long 

 plumose hairs, and a nmeh shorter third pair near the middle line ; ontside 

 of these are three pairs of very short, fine, marginal hairs. Eyes small, 

 placed on a ridge running from posterior margin to anterior corner of 

 eephalothorax ; the latter are pointed. 



Abdomen, shoulders wide and prominent ; lying between them is a central 

 wedge-shaped area; anterior part marked off by a constriction. Mandibles 

 very broad. Legs comparatively long and robust, with weak plumose hairs, and 

 without the clavate hairs present on the body. 



This species is allied to A. cloiujdtus Berlese and A. Paolii Berlese. It 

 is apparently nearest the latter species, differing from it in the much smaller 

 eephalothorax and shorter sensory hairs. Dr. Berlese has kindly sent me a 

 drawing of A. Paolii, which shows these characters much clearer than they 

 appear in the published figure (9, PI. XVIII, fig. 17). It dilTers from both of 

 these species in the more robust build and more uniform breailth of the 

 abdomen. The body hairs are not so long, and the legs are apparently 

 shorter and stouter. The sub-genus Leptalicus was established by Berlese 

 (9) without a diagnosis ; A. Paolii is the type species. 



Habitat. — I found this fragile species on at least four occasions, during 

 May and June, in the Orange Lichen zone at Malahide. It appears to live 

 in small colonies between rotten flakes where there is clay detritus. 



Nanorchestes amphibius Top. et Trouess. 



1890 Topsent et Trouessart 47. 



An abundant species in the Orange Lichen, Pelvetia, and Spiralis zones 

 on the rocky shore at Malahide. Large colonies of the larvae, nymphs, and 

 adults may be found during the summer and autumn months ; and clusters 

 of the salmon-coloured eggs are noticeable deposited round the edge of rock 

 lissures in the early summer. At Ardfry it was found on the margin of a 

 small saline pond close to the seashore. 



This is one of the few saltatorial mites, and it both runs and jumps witli 

 great activity in bright weather, even on the surfaces of rock pools. It was 

 observed at various dates from February to November. Hirst has recordeil 

 it from the Isle of Wight. A figure of the peculiar modified hairs of this 

 species is given in the present paper (I'l. XXIII, fig. 25). 



Family BDELLIDAE. 

 Bdella littoralis (L.). 

 A common and characteristic shore species. At JMalahido and Ardfry it 

 was found from the Orange Lichen down to the Vesiculosus zones, living in 



