226 HYDROPHiLiDiE. \Pararymus. 



by some authors under Hydrohms; tlieir very small size and short maxillary 

 palpi will at once distinguish them superficially ; it must, however, be 

 remembered that many of the generic distinctions are purely artificial, 

 and that in many cases it seems rather a matter of taste than of scientific 

 accuracy whether we adopt them or not. 



P. nigroaeneus, Sahl. Oval, convex, dark metallic bronze or 

 bronze-black, upper surface closely and rather strongly punctured ; 

 maxillary palpi broadly pitchy at apex ; legs pitch-black. L. 2 j-2^ mm. 



Ponds and ditches ; local and not common. Lee, Wimbledon, Esher, Woking, 

 Horsell ; New Forest ; Exeter. 



We do not possess the true P. cvncnis, Germ., which is rather smaller 

 and narrower with the palpi unicolorous red, and the legs also red. Dr. 

 Sharp also points out (E. ]\I. Mag. xxi. 112) that the structure of the 

 antennse is different in the two species. 



ANACSINA, Thomson. 



The species of Anacaina are distriljuted over the greater part of the Old 

 World ; they are distinguished from the preceding by the non-metallic 

 upper surface, and by having the base of the thorax narrowly bordered. 



I. Head black at most with a very small 

 •reddish spot on each side befoi-e eyes ; 



thorax dark with side margins lighter. 



1. Form broader; maxillary palpi and 



tarsi stouter A. GLOBULUS, VayTc. (limhata, Sharp). 



2. Form narrower ; maxillary palpi and 



tarsi more slender A. LIMBATA, F. (varialilis. Sharp). 



II. Head with a large testaceous marking on 

 each side before eyes; thorax testaceous 



•with centre of disc darker A, bipustulata, Steph. 



A. g-lobulus, Payk. (Umbata, Sharp). Oval, almost hemispherical, 

 very convex, shining, upper surface distinctly punctured ; head black ; 

 thorax black with margins lighter ; elytra fuscous or fuscous-black with 

 margins and apex lighter ; legs reddish or pitchy. L. 2|-3 mm. 



Ponds and ditches; common and widely distributed in England and Scotland. 



A. limbata, F. (variahilis, Sharp). Very like the preceding but 

 narrower and more elongate ; the mesosternum is raised behind in the 

 middle in a pointed projection, which is wanting in the preceding species; 

 the maxillary palpi are not so thick, and the tarsi are more slender ; 

 the colour of the elytra is, as a rule, but not always, lighter ; the head 

 is usually entirely black, but a variety occurs in which there is a 

 small rufo-testaceous spot on each side before the eyes. L. 2-2 1 mm. 



Ponds and ditches ; common and widely distributed in England, but local in Scot- 

 land, and only recorded from the Forth, Tay, and Solway districts. 



A bipustulataj Steph. Smaller than the two preceding species; 



