58 COPEPODA AND OTHER CRUSTACEA TAKEN IN IRELAND 



third, and fourth pairs having the inner branch considerably 

 shorter than the outer (fig. 9), last joint of the outer branch 

 longer and more slender than the preceding, all the joints 

 ciliated on the outer margins, the first two bearing a slender 

 marginal spine a little beyond the middle, last joint with two 

 marginal spines and three apical setae ; the second and third 

 joints have also on their inner margins a single long spiniform 

 seta ; the inner branch is clothed in a similar way, but without 

 marginal spines : fifth pair of feet (fig. 10) foliaceous, two- 

 jointed, first joint wide, with a produced subtruncated inner 

 plate which is armed at the apex with five setae of unequal 

 length, second joint ovate, with ciliated margins and six un- 

 equal terminal setae. The longer of the two principal tail- 

 setae is about equal in length to the entire body of the animal. 

 Length '46 mm. Male unknown. 



Hab.— On a mussel-bed between tide marks on the beach 

 at Newcastle, county Down, September, 1900. 



This species, curious both in structure and habitat, agrees 

 in most respects — in all perhaps, except in the structure of the 

 very minute mouth organs — with Ameira. These structures^ 

 however, are so extremely minute that I have been unable to 

 obtain quite satisfactory view of them, and the drawings here 

 given must be taken as being to a certain extent provisional. 

 It is very likely that when they have been more perfectly 

 investigated a new genus may have to be instituted for the 

 reception of the species. The mussel-beds in which it occurs 

 form elevated patches on the sandy beach at Newcastle, the 

 spaces between the shells being filled up with a sort of friable 

 conglomerate of sand and debris. The Copepoda were ob- 

 tained by washing a small quantity of this debris and straining 

 off the swimming or floating microzoa. This was the only 

 species found, but it occurred plentifully. 



Genus PARATACHIDIUS, gen. nov. 



Like Tachidius, but that only the first swimming foot has 

 both branches three-jointed : the second, third, and fourth 



