214 FKESH-WATEE AQUAEIA. 



is ovate in shape, and of a dark yellowish-red colour. The 

 crown and the base of the abdomen are dark brown, and the 

 thorax and the elytra are impressed with punctures. The 

 suture is dark, and there is a small line or stria on each side 

 of the base of the thorax, if. lineatocollis is also a very 

 common little beetle, and somewhat larger than the last 

 species. Its shape is ovate, its colour brownish-yellow, and it 

 may be distinguished by a dark longitudinal line upon the 

 thorax. Its elytra are punctured and faintly spotted with 

 brown. 



There is only one solitary species belonging to the genus 

 Cnemidotus, viz., C. ccesus. It is ^in. in length, ovate and 

 convex in shape, and of a shining yellow colour. Its elytra 

 are rather deeply punctured. 



The sub-family Sydroporides is represented by the genera 

 Hyphydrus and Hydroporns. The fonner genus possesses only 

 two species, one of which is doubtful, as a British insect ; 

 the latter forty- seven. 



The Haliplides and Hydroporides do exceedingly well in 

 small aquaria which contain plenty of growing plants. They 

 will not hurt tiny fish; large fish might eat them. But it a 

 fish should die, they will feed upon it until only the skeleton 

 is left. They are very useful scavengers. The water of the 

 tank in which such insects as these are kept, if they are 

 properly treated, will remain beautifully clear. These little 

 beetles will not, as a rule, hurt snails; but if one dies, they 

 will quickly empty its shell and use it as a hiding-place. They 

 do not require much feeding. 



Hyphydrus ovatus (a. Fig. 137) is a most curious-looking 

 insect, less than Jin. in length and globose in form. Its 

 colour is of a rusty red, and the thorax and elytra are 

 punctured. When captured it is often found covered with 

 mud or algse; and when out of the water, it is said to emit 

 a rather pleasant smell similar to that of honey. 



The species belonging to the genus Hydroporus are by no 

 means easy to distinguish from each other, and one of the 

 largest is H. 12-pustulatus (6, Fig. 137). This is about 

 iin. in length, and its form is oblong-ovate. The thorax. 



