122 Proceedings of the lioyal Irish Academy. 



Pachylaelaps littoralis Halbt. (PI. XXI, fig. 5 a, tl.) 



1915 Halbert 25, p. 64. 



This species was described from the male found under embedded stones 

 well below high-water mark in Eellacragher Bay, on the Mayo Coast, in 

 September, 191o. As only a single specimen occurred, there was doubt as to 

 whether the species is a true denizen of the intertidal zone. While at Ardfry 

 in June, 1910, females of a Pachylaelaps, which are evidently to be referred 

 to the present species, were met with in the Pelvetia and Spiralis zones. 



Female (fig. 5 a) : Length, 84:4/[i ; breadth, 460/u. Shape and hair armature 

 as in the male (fig. 5 e), which it also resembles in the structure of the palps, 

 legs, pcritreme, and other organs. Colour, pale yellow. Sterinim of the 

 usual shape, end corners reaciiing to the fourth acetabula; liinder margin 

 concave ; the space between this and the genital plate is weakly chitinized. 

 The genital plate is lai^e, pointed in front, and evenly nuindcd behind, 

 though occiisionally somewhat truncate. Anal plate broader than long 

 (breadth, 140/i; length, 120/j) ; extremity strigose. Peritreme enclosed in a 

 plate forming a narrow margin on its outer side; end of plate acuminate, 

 reaching well beyond the middle of ventral plate. All these plates are 

 reticulate and punctureil. 



Maxillary plate narrow, wiih two pairs of long hairs on front margin and 

 two shorter proximal pairs; maxillary lobes straight and very long, reaching 

 end of liypostome. Epistome with about eight spines, some branched. Each 

 chela armed with one strong tootli. Legs, second pair stout (length about 

 410^), segment two, with a small conical tooth. Tiie armature of the tarsus 

 is figured (tig. 5 b). 



'riie male of this species has a broad dagger-like process on the free 

 clielicerae, and the femur of the second legs carries a stout conical spur 

 (fig. 5 d.'. 



Habitat. — Found on the shore of Mweeloon Bay, Ardfry, under stones 

 on gravel and sandy mud in the Pelvetia and Vesiculosus zones, June, 1916. 



Tietzc records the occurrence of a single .=ipecinien of Pnrhi/lrielaps 

 jKclmifi-r, which he found umlcr stones on the seashore at Venice (46). 



Macrocheles marginatus, var. littoralis ("Halbt.). 



1015 Iloloslasjm iiianjiiuiliis, var. liltomiis, Halbert 25, p. 67. 



The variety was described from females and an immature male found on 

 the seashore at Westport. It has also occurred at Malahide under stones 

 and refuse in the Orange Lichen zone, and at Ardfry under stone.s resting on 

 mud in the same zone. It seems a rather common form at the high-water 

 level. 



