Hai.bkkt — The Acarina of the Seashore. 133 



Oribatula similis Micliaol. 



Found in the Pelvetia zone and upwards at Avdi'ry, under stones resting 

 on a peaty soil, dryish wlien llie tide recedes, but Hooded at high tides. Also 

 under stones on a grassy sward, just above the I'elvetia zone, June ; occurs on 

 the seashore at Baldoyle in a similar habitat. A generally distributed 

 British species. 



Oribatula venusta Berl. 



1908 Berlese 12, p. 8. 1910 Berlese 10, p. 229. 1910 Halbert 25, p. 102. 



This is evidently a coast species in Ireland, though Berlese does not state 

 the habitat of the original Norwegian specimens. It was first recorded as a 

 British species from the Mayo coast (25), where it is quite common under 

 stones a little above high-water mark, and also on the adjoining sandhill, in 

 September. At Ardfry it occurs under stones resting on sand and decayed 

 seaweed in the Orange Lichen zone, June, 1916. At Malahide under hard 

 limestone flakes in the lower part of the Orange Lichen zone in company with 

 Ochthebius Lcjolcsii, and other littoral species. I have also found it on 

 Lambay Island in October, and amongst lichens and moss on the Portmarnock 

 sandhills in January. 



Oribatula saxicola sp. nov. (PI. XXII, fig. 16 a, b.) 



A small sluggish species belonging to the " tibialis " section of the genus 

 Oribatula. Lives in rock fissures. Length, 490;u ; breadth, 286;u. Colour light 

 brown. Body strongly flattened, surface apparently smooth and shining, 

 but in reality excessively minutely punctured. Cephalothorax (fig. 16a) 

 comparatively large, rostrum bluntly pointed, lamellae narrow blades on edge 

 and tapering to a point, placed partly on the marginal slope of the cephalo- 

 thorax ; lamellar hair long and minutely setose, it springs from a pore lying 

 immediately in front of the extremity of the lamellae. Translamella absent, 

 or a mere line. The pseudostigniata are hidden under the dorsum, though 

 occasionally the corners project a little. Pseudostigmatic organs (fig. 16 h) 

 with slender stalks and strongly chibbed extremities. 



Abdomen with the shoulders evenly expanded ; breadth about Iwu-thirds 

 of the length. On the dorsum there are three or four pairs of pores and 

 short hairs, and at least thi-ee pairs of upturned marginal hairs are noticoablo 

 on the posterior third of the body. Legs robust and a litile longer than in 

 0. tibialis ; claws unequal. 



The following notes may be of use in separating the present from the 

 allied species: — From 0. slmUis (Michixn]) easily recognized by the tridactyle 

 claws. From tibialis (Nicolet), to whicli it is nearly allied, by tlie shorter 



