HARPACTICUS. 151 



(fig. 11) about as long as broad, and the inner of the 

 two principal tail-setse is excessively long, being quite 

 equal in length to the whole body of the animal. 

 Length -^rd of an inch (I'l mm.). 



Considerable interest attaches to this species on 

 account of its wide geographical distribution. It 

 is restricted almost exclusively to the uppermost 

 margin of the littoral zone, haunting more especially 

 shallow pools at or above high-water-mark, and often 

 occurring in prodigious numbers towards the end of 

 summer when the water has become warm with 

 prolonged exposure to the sun. In such situations it 

 occurs almost everywhere round the British Islands, 

 and has been found by Continental naturalists in 

 various places on the coasts of the Baltic and North 

 Seas. I have also had specimens sent to me 

 from Kerguelen Island in the southern hemisphere, 

 where it was found by Mr. Eaton of the " Transit of 

 Venus Expedition." Some specimens which are 

 indistinguishable from H. fulvus were dredged by Mr. 

 Robertson and myself in a depth of thirty-five fathoms 

 off the Yorkshire coast, and were noted by us in the 

 British Association Report for 1875, as a new species 

 under the name H. crassicornis. This name must, 

 however, now be withdrawn, as, notwithstanding the 

 unusual nature of the habitat, there seems nothing to 

 separate these specimens from the species now under 

 consideration. In one fresh-water locality (Kinny 

 Lough, County Donegal) we have found this species ; 

 but there is little reason for surprise here, the Lough 

 being in close proximity to the sea, almost on the sea- 



