Head beneath, with a deep groove on each side near the eye for the reception of the antennae or a part thereof. Sub-fam. 3. Pseudomorphides. Head without antennal grooves. Sub-fam. 2. Harpalides. 2. Middle coxal cavities attained on the outside by the tips of the episterna and epimera. Sub-fam. 4. Mormolycides. 3. Middle coxal cavities attained on the outside by the tips of the epimera, but not by those of the episterna. Sub-fam. 1. Carabides. These four sub-families are of extremely different extent and nature. The Harpalides are the dominant forms, and include upwards of 10,000 known species; while the various tribes into which the sub-family is divided include, as a rule, each many {207}genera; the Carabides are next in importance, with upwards of 2000 species, but are divided into a comparatively large number of tribes, each of which averages a much smaller number of genera than do the tribes of Harpalides; Pseudomorphides includes only about 100 species; and Mormolycides consists of the single genus _Mormolyce_ with three species. FAM. 6. AMPHIZOIDAE.—_Antennae destitute of pubescence: outer lobe of maxilla not jointed; metasternum with a short transverse impressed line on the middle behind. Hind legs slender, not formed for swimming._ This family is limited to the genus _Amphizoa_; the species of which may be briefly described as lowly organised Carabidae that lead an aquatic life. The geographical distribution is highly remarkable, there being but three species, two of which live in Western North America, the third in Eastern Tibet. The habits of American _Amphizoa_ are known; they pass a life of little activity in very cold, rapid streams; they do not swim, but cling to stones and timber. The larva was recently discovered in Utah by Messrs. Hubbard and Schwarz:[90] it has the same habits as the perfect Insect, and in general form resembles the larvae of the genus _Carabus_; but it has no terminal tube to the body, the abdomen consisting of eight segments and a pair of short terminal appendages; the spiracles are obsolete, with the exception of a pair placed near to one another at the termination of the eighth abdominal segment. As regards the mouth this larva is Carabid, as regards the abdomen and stigmata Dytiscid of a primitive type. [Illustration: Fig. 93—_Amphizoa lecontei._ North America. A, Larva; B, imago.] {208}[Illustration: Fig. 94—_Pelobius tardus._ Britain. A, Young larva; B, adult larva; C, imago. (A and B after Schiödte.)]