39 108 Proceedings of the Royal Irish Academy. 



Hoploderma magnum (Nicolet). 

 Clare Island, Achill, and Westport district. Abundant in moss, amongst 

 fallen pine needles, and under bark. 



Distribution. — Germany; Holland; France; Britain. 



Hoploderma dasypus (Ant. Duges). 

 Clare Island, Achill, and "Westport district. Common 

 Distribution. — Finland to North Africa (Algeria). 



Phthiracarus arduus (C. L. Koch). 

 Clare Island, in sphagnum and under bark. 

 Distribution. — Finland; Germany; Holland; Britain. 



Sub-order SARCOPTOIDEA. 

 Family HYAUESIDAE. 

 Hyadesia fusca (Lohm.). 



1894. Lentungula fiisca Lohmann 43, p. 86. 1899. L. fusca Canestrini 

 and Kramer 26, p. 136. 1901. L. fusca Michael 51, p. 196 (reference). 

 1907. H. fusca Lohmann 45, p. 368. 



A number of specimens were found amongst coralline seaweeds in rock- 

 pools on the coast of Clare Island in July, with sea mites of the genus 

 Ehombognathus. 



This would appear to be the first recorded occurrence of this marine 

 species on the coasts of Britain. It is closely allied to H. algivorans, 

 described by Michael (51) from brackish water on the coast of Cornwall. 

 Lohmann separates the two northern 1 species as follows : — 



Stalked claw of the first leg very small, much shorter than the strong end 

 claw of the fifth leg segment ; claw of the first pair of legs much shorter 

 thau that of the second pair ; claw of the last pair of legs without adjacent 

 tooth at the base. Length of female 380ju, . . H. algivorans (Mich.). 



Stalked claw of the front legs only a little shorter than the strong end 

 claw of the fifth leg segment ; claw of the first two pairs of legs of about 

 equal length. Length of female 530ju, . . . H. fusca Lohm. 



Apart from its larger size H. fusca may also be known by the presence of 

 a narrow chitinous plate on the front margin of the body, and the palpus has 

 only two free segments. The Clare Island specimens agree in every respect 

 with H. fusca except that they are a shade smaller. 



1 Two other species are found in the southern ocean, i.e., S. uncinifer Hegnin at Tierra del 

 Fuego (47), and S. kergtieleitsis Lohmann amongst algae on the coast of Kerguelen (45). 



