THE BLACK WATER BEETLE. 109 



The Beetle belongs to the family of HydrophilidsB, i.e. 

 water-lovers. Sometimes the two halves of the word are 

 transposed, the Beetles being called Philhydrida, the significa- 

 tion being exactly the same in both cases. The family may be 

 known by the size of the palpi, which are as long as the 

 antennoe and sometimes longer — the latter organs never having 

 more than nine joints, and sometimes only six — and by the 

 double lobe of the maxilla and the very short mandibles. The 

 tarsi have five joints. The typical genus has the mandibles 

 armed on the inside with three strong teeth, notched at their 

 tips ; the second joint of the maxillary palpi is very long, and 

 the elytra become narrower towards the apex. 



The insect is represented on Woodcut XII. Fig. 4, of its 

 natural size, showing that, with the exception of the Stag 

 Beetle, it is our largest coleopterous insect. A glance at the 

 figure will show one of the principal peculiarities of this 

 Beetle, namely, that the palpi far exceed in length the an- 

 tennae, and projecu in front considerably before those organs. 

 The sexes are easily distinguished by a glance at the antennse, 

 and the tarsi of the first pair of legs. The antenna of the male 

 is drawn on the same woodcut, Fig. e, and in the same sex the 

 last joint of the front tarsi is very much dilated, and assumes 

 the form of a partly flattened triangle. The same limb in the 

 female does not possess the widened joint, and may be seen by 

 reference to Fig. d. The metasternum terminates in a sharp 

 spine, so long that its point reaches beyond the coxae of the last 

 pair of legs. 



The colour of this Beetle is smooth blackish- olive, the 

 margins of the elytra taking a bluish tinge. The wings them- 

 selves are very large, and have a very fine effect when spread. 

 On each of the elytra are eight stria, and the breast is clothed 

 with thick yellow down. The metasternum is developed, as in 

 the Dyticus, into a pointed process, but in this insect the 

 weapon is simply needle-shaped, and is about the size of an 

 ordinary darning-needle. It is black, highly polished, and very 

 sharp. There is much variation in' tint in different individuals, 

 but the average hues are as given above. 



The life history of this insect is a very curious one. The 

 female Beetle is furnished with a complete silk-spinning appa- 

 ratus, the spinnerets being placed, not in the mouth, as is the 



