membranous, or coriaceous, instead of horny like the rest of the surface. The upper surface is divided into regions, the back part being called the occiput, the middle the vertex, and the anterior the front; on each side are the eyes.

The eyes of Coleoptera are very variable in form and shape, and are composed of aggregated small lenses; rarely they are entirely wanting; equally rarely accessory eyes are seen, in the form of one or two simple lenses; they are situated between the compound eyes, on the upper surface, and are called ocelli.

The under surface of the head is widely excavated, forming the mouth; the parts beneath the eyes and behind the mandibles are called the genæ; behind the mouth the region is called the throat, or gula; the suture separating the gula from the mentum (hereafter described) is called the gular suture; from the opening of the mouth may be seen two sutures, which sometimes unite at the medial line, running backwards; these are called buccal sutures; they are of but small interest in classification, but I have made use of their position to define the groups of the sub-family Telephorida.

ANTENNE.-The antennæ are articulated appendages inserted in front of, or more rarely, between the eyes-usually under the side margin of the front; they vary in form and number of joints, the latter attaining, in our fauna, the minimum in Adranes, of the family Pselaphidæ, in which genus they consist of but two joints; the maximum is reached in certain species of Prionus, of the family Cerambycidæ, where 25-27 joints are seen. The usual number of joints is eleven; the joints nearest the head are usually of denser consistence than the outer ones, which possess a peculiar structure, intended for special sensibility. It consists in an immense number of pores, visible only under a very high magnifying power, and covered by a very delicate transparent membrane. These pores vary in situation in different families, but it is not yet known how far these variations may be used for purposes of classification. Lacordaire has found them of service in grouping the genera of Buprestidæ.

The forms of antennæ may be reduced to the following types :1. Filiform, where the joints are cylindrical, and the outer ones are not, or scarcely enlarged; when the outer ones are somewhat more slender, the antennæ are said to be setaceous.

2. Serrate, where the joints are triangular and compressed, presenting therefore a serrate outline on the inner margin; the outer joints (usually three in number) are sometimes enlarged, forming a serrate club; the form varies by insensible gradations (as in the family Clerida), from the regularly serrate form and the very flattened serrate club, to the small and more compact club of Corynetes; whereby we pass to the next type. Other variations of the serrate type are :—

a. The joints are short, and very much prolonged on the inner side, giving the pectinate, or on both sides, giving the bipectinate form; when these prolongations are very long compared with the antennæ, the flabellate form results.

b. The joints emit from the base or apex, sometimes on one, rarely on both sides, cylindrical branches; the antennæ are then called ramose; if the branches are very long and flexible, they are called plumose.

3. Clavate, where the outer joints are more or less enlarged, but not triangular, nor leaf-like. This is one of the most usual forms of antennæ, and its modifications connect insensibly with all the other types; names are therefore necessary for the purpose of more definite description. The principal forms are as follows:

a. Moniliform or granose, when the joints, not differing greatly in size, are rounded, resembling a string of beads; this leads to the filiform type.

b. Clavate, where the outer joints are gradually larger, forming an elongate club.

c. Capitate, where the outer joints are suddenly larger, forming a compact rounded club; this leads gradually to the last type, 4. Lamellate in this the outer joints are prolonged internally, opposing flat surfaces to each other, which may be brought closely in contact, forming thus a transverse, or rarely rounded, club, supported at one side by the stem of the antennæ. This form obtains in all Scarabæidæ.

Antennæ are called geniculate when the second joint is affixed so as to make an angle with the first; the following joints continue in the line of the second.

Other names have been applied to modifications in the form of antennæ, but they are of rare occurrence in the literature of the science, and are not used in the present treatise.

ANTENNE: 1. Serrate; 2. Pectinate; 3. Capitate (and also geniculate); 4, 5, 6, 7. Clavate; 8, 9. Lamellate; 10. Serrate (Dorcatoma); 11. Irregular (Gyrinus); 12. Two-jointed antenna of Adranes coecus.

MOUTH.-The mouth of Coleoptera is mandibulate; that is to say, it possesses two pairs of horizontally moving pieces for the purpose of seizing the food. Above it is seen a small piece articulating with the front or epistoma, which is called the upper lip, or labrum.

Immediately below the labrum are the jaws, or mandibles; they are of various shapes, but are generally curved and of moderate size; exceptionally, in certain Lucanidæ, they are very long and branched, like the antlers of a deer; at other times, as in certain Scarabæidæ, they are very small and partly membranous. The form of the joint between the mandibles and the head varies somewhat, and has been used by Duval for the purpose of defining some genera of Buprestidæ.

Below the mandibles is a second pair of horizontally moving pieces, called maxilla; they are complex in structure, and are of great moment in classification, and therefore demand a special paragraph.

MAXILLE. The hind portion or base of the maxillæ is composed of two pieces; the one articulating with the head is called the cardo, the second piece the stipes; attached to the stipes are the appendages, which are normally two lobes and one maxillary palpus; the lobes are varied in form, according to the families and genera, and sometimes one or the other is so small as to be indistinct; the outer lobe is occasionally, as in Cicindelida, Cara

bidæ, and Dytiscidæ, slender, and usually divided into two joints like a palpus, whence in the older books the insects of those families are said to have six palpi. The inner lobe is, by a rare exception, as in most Cicindelidæ, terminated by a movable hook. The maxillary palpi are usually 4-jointed, rarely 3-jointed, and in the genus Aleochara alone 5-jointed, by the addition of a very minute terminal piece; they vary in form, being filiform or dilated, and are occasionally of great size, as in most Pselaphide; sometimes very long and slender, as in most Hydrophilidae; the last joint is frequently much smaller and more slender than the penultimate, in which case the palpi are called subulate.

ANTENNE: 1. Bipectinate; 2. Flabellate. MAXILLE: 3. Bembidium; 4. Hydrophilus; 5. Pselaphus. MAXILLARY PALPI: 6. Ctenistes; 7. Tmesiphorus; 8. Tychus.

MENTUM AND LIGULA.-Beneath the maxillæ, and between them, is seen a small movable piece called the ligula, which supports two articulated appendages called the labial palpi; behind them is a large or small corneous plate, forming the floor of the mouth-it is called the mentum, and articulates with the lower surface of the head by the gular suture, which is rarely effaced; the openings each side of the mentum are called buccal openings. The mentum and ligula are very important organs in the system. of classification.

The mentum is usually small, or moderate in size, and trapezoidal or quadrate, but frequently of large size, and varies accord

ing to the family; rarely it is so large as to close over the buccal openings, and thus conceal the base of the maxilla; it is frequently, as in Carabidae and allied families, deeply emarginate in front, with a prominence called a tooth at the middle of the emargination; the presence and form of this tooth are of generic value. In many families, especially those with antennæ of the clavate and serrate types, the mentum appears to be divided into two portions; this results from a piece between the mentum and ligula, called the hypoglottis, and which is usually entirely concealed, coming into view by reason of increased development.

The ligula is either corneous or membranous, usually oblong, pointed, rounded, or emarginate, or even cleft and lobed at the anterior extremity; usually prominent, rarely concealed behind the mentum; near the tip is usually seen on each side a membranous process; these are called paraglossæ, but are frequently wanting. Between the body of the ligula and the mentum are the supports of the labial palpi; these sometimes are largely developed, and in certain Scarabæidæ are entirely united together, forming what appears to be the ligula; the genuine ligula in these cases is almost atrophied, and is concealed behind the corneous plate formed by the labial supports. In the following pages the term ligula is used in both cases, and is to be understood to mean the piece in front of the mentum bearing the palpi, whether it be the ligula proper or some other part.

The labial palpi are usually 3-jointed, but occasionally 2-jointed or even (certain Staphylinida) filamentous, and not divided into joints. In the genus Aleochara they become 4-jointed, by the addition of a very minute terminal joint. They vary in form.

THORAX.

The second division of the body is called the thorax, and consists of three segments which support legs, and which are variously modified as regards size and union in the different orders of insects.

In Coleoptera the first of these segments, the prothorax, is separate from the other two, and is freely movable; it consists of a dorsal surface, the pronotum, consisting normally of four pieces, which in Coleoptera are never distinct; two pairs of pieces form