300 NATURAL HISTORY. 



period, Coleoptera are found in the Lias in some abundance, and of such definite forms that they have 

 been referred without hesitation to many of the modern families Carabidte, Qyrinidse, Hydrophilidse, 

 Scarabaeidse, and so forth ; in the lower marls of the Lias in the Swiss Alps no fewer than thirty -three 

 species of Buprestidae have been found, two of them supposed to belong to genera which still exist. 

 The resemblance to existing genera is carried still farther in the Oolite and in the Upper Eocene ; and 

 in the Lower Miocene it becomes so close that the numerous Beetle fossils found in beds of this 

 formation in Centr-al Eiu*ope belong for the most part to genera which still inhabit the same countries. 



SECTION I. PENT AM ERA. BEETLES WITH FIVE-JOINTED TARSI. 



TRIBE ADEPHAGA. 



The first tribe of the order Coleoptera, or the Adephaga, is distinguished from all others by an 

 organisation specially adapted to carnivorous and predaceoiis habits. The general form of body is 

 slender, the three chief segments head, prothorax, and hinder-body having free play, and the limbs 

 are constructed for rapid locomotion. All have five joints to the tarsi ; the haunches of the first two 

 pair of legs are rounded, and move in rounded sockets ; the abdomen beneath is composed of six or 

 seven segments, of which the first three are soldered together; and the antennae are always slender 

 and light, being thread-shaped, or tapering to the apex, composed of eleven sub-cylindrical joints, and 

 never club-shaped at the tip. But the chief points of distinction from other tribes reside in the parts 

 of their moxith, as in the analogous case of the dentition-characters of the order Carnivora in the 

 Mammalia. The maxilla are horny and generally hooked, forming a second pair of instruments for 

 cutting and tearing, and their outer lobes are transformed into an additional or third pair of palpi. 

 The mentum, or chin, is always well developed, and of definite form and outline, being horny through- 

 out, with a free upper margin, excised in the middle, and often armed in the centre of the angular 

 excision with a tooth. From its upper inner edge rises the ligula, or tongue, generally an oblong and 

 angular horny plate, flanked by the adherent slender paraglossa?, and fronted at its base by the labial 

 palpi. The Adephaga are distinguished generally from all other sections of the order by the sharply- 

 defined form of all the parts of the mouth, and the ease with which they may be examined. Within 

 the limits sketched out by the above characters, they are subject, as^well as other parts of the structure 

 of the insect, to great modification, in correspondence with the greatly-diversified modes of life of the 

 countless members of the group. The section is composed of four families, viz., Cicindelidae, Carabidae, 

 DyticidaB, and Gyrinidse, which are re-combined by many authors under two sub-sections according to 

 their mode of life; one named Geodephaga, or Land-beetles, comprising the first two families ; the other 

 Hydradephaga, or Water-beetles, including the last two. 



FAMILY CICINDELID.E, OR TIGER-BEETLES. 



CiciiidelidfK are the elegantly-formed and nimble insects known popularly as " Tiger-beetles." 

 The raptorial type of structure is in them carried to a high degree of perfection. Their eyes are large 

 and prominent, and all their movements show extreme wariness. Most of them make i-eacly use of 

 their wings in flying, besides being endowed with remarkable speed of foot, and their mouths are well 

 adapted for seizing and retaining their prey, their mandibles, or upper jaws, being long, and furnished 

 with mimei'ous sharp teeth, and their maxillae and palpi studded with rigid bristles, which retair 

 from the sides and beneath anything transfixed by the mandibles. With regard to other organs of the 

 mouth, they differ from Carabidse in the greatly diminished size of the lower lip, which does not 

 project beyond the edge of the mentum, and in the basal support of the labial palpi being articulated, 

 forming a fourth joint. These lip-palpi, in fact, from their length, and, in many cases, the width of 

 their joints, added to the rows of bristles with which they are furnished, supply the place of the 

 mentum, in closing the orifice of the mouth from below, thus furnishing one of those cases of 

 compensation which are so frequently observed in insect structure and functions. The last feature in 

 the mouth-structure which we need notice is the articulated horny hook at the apex of the maxillae, 

 which distinguishes nearly the whole of the family from all other members of the section, in which the 

 hook or point is simply the terminal portion of the blade. 



Tlie number of species of Tiger-beetles at present known is not much less than 1,000, classified 

 under five sub-families and about forty genera. They are found in all the warmer parts of the earth, 

 with the exception of oceanic islands ; and some species range as far north as Lapland. The majority 



