I9I2. Brownk. — Aquatic Coleoptera of S.E. Ireland. 3 



Also in aenescens the metasternum is distinctly keeled in 

 the median line, while in guttiger there is a mere rudiment of 

 a keel and in some specimens none at all. The coxal 

 processes in both species have a distinct keel down their 

 median line. 



The Irish records for Limnehius papposus are for Donegal 

 East, Armagh, Down and Dublin. The records for the first 

 three counties are b}' Johnson, while the Dublin record is 

 by M'Nab, who mentions the species as having been taken 

 in the Dodder River^ Mr. Johnson kindly allowed me to 

 see all his water-beetles, and I have also seen the Dublin 

 Museum collection and all Irish specimens standing as 

 L. papposus are in reality L. truncatellus. There is a great 

 deal of confusion with regard to these two species, especially 

 in the case of the females which, on the characters usually 

 given are very difficult to separate. There is, however, one 

 character by which these may be easily distinguished and 

 that is the form of the mesosternal process. In L. tnm- 

 catellus this structure is broad, does not taper and is nearly 

 Hat, while in L. papposus it is narrow, tends to taper and 

 is slightly grooved. 



Several changes have been made as to synonymy since 

 1901, which have tended to make a number of records 

 useless. Edwards ^ has shown that the Haliplus ruficollis 

 of British authors includes several species and some of these 

 are recorded in this paper. Laccohius sintiatus, Mots., which 

 was formerly regarded as synonymous with L. nigriceps, 

 Thoms., is now recognised as distinct, but Dr. Sharp has 

 recently come to the conclusion that Motschulsky's name 

 should be dropped as his description is too vague to apply 

 to any one species and has suggested that our so-called 

 sinuatus should in future be known as ytenensis^. 



The fact that Helophorus porculus, Bedel, has only recently 

 been recognised in Britain as distinct from H. rugosus^ 



I British Association Guide, Dublin, 1878. 



» A Revision of the British Species of HaUplus, Latreille. Ent. Mo. 

 Mag., ser. 2, xxii., Jan. 191 1. 



3 A new Species of Laccobius. Enf. Mo. Mag. (2), xxi., p. 250, 1910. 

 * E. A. Newbery, Ent. Mo, Mag., ser. 2, xix., p. 88, 1908. 



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