214 The Irish Naturalist. August, 



our insular fauna ; yet, till a much more complete acquaintance 

 has been made with the contents of our marshes and meres, 

 it seems wiser to defer drawing any inferences from such a 

 fragmentary and imperfect instalment of facts as is now in our 

 power to offer. Nevertheless what has been ascertained seems 

 highly suggestive, and should encourage careful and active 

 research into this fruitful though neglected field. 



SSda crystalllna, O. F. Mull. — This species is not rare in the lakelets 

 and pools of the Counties of Monaghan, Fermanagh, Donegal, Sligo, 

 Clare, Gal way, and Leitrim. Abundant in Loughs Erne, Neagh, 

 Ree, Corrib, Mask, Arrow, and Melvin. In the reaches of Upper 

 L. Erne, where Stratiotes abides has made a settlement, this species 

 clings to its leaves in enormous numbers. 



Diaphanosoma brachyurum, lyievin. — L. Ballinahinch and 

 Kylemore, Connemara ; Lisdoonvarna, Co, Clare.' 



D. leuchtcnbergrianum, Fisch. — L- Gill, very abundant ; Lower L. 

 Erne, abundant; Ballynahinch, Kylemore, and Clifden, Connemara ; 

 Boyne Canal. 



Holopedium g-ibberutn, Zadd. — Ballinahinch, Connemara, abun- 

 dant ; L. Mask, a few. 



Daphnia pulex, De Geer,— Everywhere common. Var. hamat. 

 occurs at Drumreaske, as identified by Mr. Scourfield. (Dr. Creigh 

 ton's record of var. obtiisa he considers to require confirmation.) 



D. Iong:ispina, Mull.— Glaslough, L. Bawn, and elsewhere in Co. 

 Monaghan ; Lower L. Erne, L. Gill, Clifden lakes, near Galway 

 (vi.) ; lakes of Fermanagh and Donegal (ix.), Boyne Canal ; L Gur, 

 Co, Limerick. 



(Z>. psittacea, Baird.— Drumreaske. Identified as probably this species 

 by Canon Norman.) 



D. hyalina, var. lacustris, G.O.S.— Dartrey, Co. Monaghan, 

 abundant ; L. Neagh, do. ; Upper L. Erne, a few with D. cucidlata ; 

 L. Mask and L. Ree, abundant. 

 Sub-species graleata, G.O.S.— Ballinahinch, very abundant; Kyle- 

 more in Connemara; L. Mask, near Galway (vi.), L. Melvin (ix.), 

 L. Gill, L. Arrow, very abundant ; L. Ree, do., etc. 



1 A Diaphanosoma, apparently hitherto undescribed, exists among 

 the plankton of L. Mask, Co. Mayo. Its most salient characters are 

 as follows :— It agrees with D. brachyurnm, Lievin, in the comparative 

 shortness of the second antennae relatively to the test. Instead 

 however, of the head being in the direction of the long axis of the body 

 the distal half bends forward at an obtuse angle to the back, and is 

 narrowed and contains the eye. The length of the first pair of antennae 

 with their seta exceeds the total length of the head. The first example 

 of this species I concluded was a monstrosity, but further examination 

 revealed numerous other examples with the same characters. 



