The first notice of the type of this very anomalous group of insects appeared in a note appended to a paper of mine in the I8-th number of the "Zoological Journal," (published in 1S30,) in which I regarded it as a connecting link between the Prionidae and Lucanidae, agreeing with the former in its general appearance, short trigonate advanced mandibles and moderately long antenna:, whilst in the internally produced structure of the three terminal joints of the antennae it agrees with Lucanus observing, moreover, that the joints of the tarsi are cylindric (as in the latter), but the insect is heteromerous ! Shortly afterwards a figure of the type Trictenotoma Childrenii was pubhshed from a drawiug of mine in the plates to Griffith's edition of the "Animal Kingdom," and M. Guerin Meneville also gave a figure of it in his " Magasin de Zoologie," pi. 35, with a notice by M. Dupont in which the position of the genus was considered to be " en tete des Longicornes, famille on, par tous ses rapports il entre tout naturellement." During the period which has since elapsed no further attempt has been made to investigate the affinities of the genus by an examination of its structural characters. Having, however, recently received a specimen of T. Childrenii from Assam by the kindness of Major Jenkins, and two other new and very distinct species having also been recently received in this country, I have submitted the whole to a careful investigation, the result of which is before the student in the accompanying plate. From the considerations derived from the structure not only of the mouth organs but also the position of the wing veins and numerical arrangement of the abdominal segments, I have no longer any hesitation in referring the insect to the section Longicornes, notwithstanding the internally produced terminal joints of the antennae (which is too trivial a character to be considered of high importance in limiting the groups), the heteromerous tarsi, and the structure of the organs of generation. Moreover, its nearest affinities appear to be the Prionidae, especially in the poi-rected head and mandibles, moderately short antennae, slightly emarginate eyes, and wing veins. From these, however, it difi'ers in several respects, so that I have considered it more natural to regard it as the type of a distinct family, which may be thus characterised. TRICTENOTOMIDAE. Westw. Head horizontal ; eyes transverse, slightly emarginate behind the base of the antennae ; labrum short, transverse; mandibles porrected, nearly alike in both sexes. Maxillae with the inner lobe scarcely produced, outer lobe long, narrow, and haiiy ; mentum broad, with the sides elevated ; labium short, bipartite ; antennae moderately long ; those of the males rather more elongated ; three terminal joints internally serrated. Pronotiun with the hind margin lobed in the middle ; wings folded at about threefourths of theii" length from the base ; abdomen with seven dorsal and five ventral segments ; the terminal dorsal segment in the male notched ; the terminal ventral segment in the same sex more deeply I 2 notched ; the last dorsal segment of the female elongate-conic and notched ; the last ventral segment in the same sex entire ; ventral surface of the sheath of the male organs deeply notched ; the latter furnished with two long slender horny filaments ; sheath of the ovipositor of the female flattened and furnished with two slender hairy filaments; legs moderately long; all the tibice entire along the external margin, and with two minute apical spurs ; tarsi sub-cylindric, heteromerous, the underside of each joint clothed with a short velvety pad ; body more or less clothed with a delicate pubescence. The family consists at present of the single genus Trictenotoma, of which I have now the pleasure to describe three species.

FIGURES I & 2.—Species 1. TRICTENOTOMA CHILDRENII. G. R. Gray in Griflf. An. K. pl. 5 & 5*. 3. Trictenotoma nigra, supra undique griseo-luteo pubescens, mandibulis (in utroque sexu) subfalcatis, antennis pedibus maculisque duabus elevatis prouoti nigris hujus lateribus sub-angulatis, scutello triangiilari. Trictenotoma blael;, covered on the upper surface nitU luteous-grey pubescence, the mandibles (in both sexes) subfalcate, antennse, legs, and two elevated spots on the pronotum, black ; the sides of the latter somewhat angulated ; and the scutellum triangular. Length of the insect 11 to 2J inches. Inhabits various pai-ts of India. In the Collections of the British Museum, Zoological Society, Hope, Pan-y, Westwood, &c. Figure 1. The female of the natural size; la, the last ventral segment of the abdomen with the last dorsal segment extending beyond its extremity; lb, Ic, sheath of the ovipositor. Figure 2a, head of the male; 2b, maxilla (1 cardo, 2 stipes, 3 mando, 4 squama palpigera, 5 galea, 6 palpus.) 2c, 2d, 2e, instrumenta labiaHa in different positions; 2 f under-side of abdomen of this sex; 2g, under-side of sheath; 2h, last dorsal segment of abdomen; 2i, upper side of sheath; 2 k, 21, inner sheath ; 2 m, male organ; 2 n, apex of ditto.

FIGURE 3.—Species 2. TRICTENOTOMA TEMPLETONII. Westw. J Trictenotoma nigra supra luteo-albido pubescens, mandibulis maris e.vtus viilde sinuatis dente magno subapicali erecto armatis, antennis pedibus maculisque duabus elevatis pronoti nigris hujus lateribus angulatis, scutello triangulari. Trictenotoma black, above clothed «ith a luteous-buff pubescence, the mandibles of the male outwardly much sinuated, and ai-med near the apex with a large upright tooth ; the antenna;, legs, and two elevated spots on the pronotum shining black, the sides of the latter angulated and the scutellum triangular. Length of the insect nearly 2J inches. Inhabits the island of Ceylon. In the Collection of R. Templeton, Esq. Figure 3. The male of the natural size; 3 a, the last ventral segment of the abdomen, showing the extremity of the last dorsal segment, which is scarcely emarginate; 3 b, the under-side of the sheath 3c, male organ; 3d, apex of ditto.

FIGURE4.—Species 3. TRICTENOTOMA AENEA. Parry. MSS. ? Trictenotoma nigra subnitida ; elytris seneis vel cupreis pubeseentia tenuiori albida induta, mandibulis extus subsinuatis, pronoto utrunque subserrato et pone medium spina acuta armato, disco utrinque tuberculo ti'ansverso subelevato, scutello brevi. Trictenotoma black, somewhat glossy, the elytra brassy or coppery, the upper surface more slightly clothed with a buff pubescence, the mandibles outwardly subsen'ated, the pronotum sUghtly serrated at the sides iu front and with a sharp spine on each side beyond the middle, the disc with a slightly elevated transvere tubercle on each side, and the scutellum short. Length of the insect 3 inches. Inhabits the Himalayas. In the Collections of Captain Parry, Dr. Benson, and T. V. Wollaston, Esq. Figure4. The female of the natural size; 4a, the under-side of the head; 4 b, the last ventral segment, showing the extremity of the last dorsal one ; 4 e, the last dorsal segment ; 4 d, sheath of ovipositor