BEETLES. 35 



and rise to the surface from time to time to take in air. They 

 may be brought to the top of the water by stirring up the mud 

 at the bottom, and can then be caught with a net. 



Genus Hydrophilus, Fabr. 



Antennte with nine joints, the second being conical. The 

 point of the metasternum projects far beyond the hind coxae. 

 They are large smooth beetles, and are common in standing 

 water almost all the year through. 



* H. piceus, Linn. (Plate IV., Fig. 16). Wing-cases with a 

 small pointed tooth. The ridge beneath the thorax is deeply 

 grooved in front. The larvae feeds on water-plants, but the 

 perfect insect preys upon aquatic insects and fish-spawn. The 

 eggs are laid in a shining silvery sac, which floats on the 

 surface of the water. It is very local. 



Genus Hydrobius, Leach. 



Body oval, or elongated ; hind tarsi only slightly compressed. 

 The last segment of the maxillary palpi is longer than the one 

 preceding. They abound in standing water, at the roots of 

 aquatic plants. 



* H. {Hydrous) carahoides, Fabr. (Plate IV., Fig. 17). This 

 species is black and convex. The hind tarsi are strongly 

 compressed and ciliated. It is common in stagnant water. 



* ff. fuscipcs, Linn. (Plate IV., Fig. 18), is moderately con- 

 vex, black, or pitchy-brown. The elytra are punctate-striate, 

 with a row of larger punctures. Length, 8 mm. Common. 



H. glohulics, Payk. This little species is only 3-4 mm. in 



length. It is brown, with the elytra more distinctly punctate 



than the head and thorax. It is widely distributed. 



D 



