There are a considerable number of blind members of this family: some of them live in caverns; these belong chiefly to the genus Anophthalmus, species of which have been detected in the caves of the Pyrenees, of Austria, and of North America. It has been shown that the optic nerves and lobes, as well as the external organs of vision, are entirely wanting in some of these cave Carabidae; the tactile setae have, however, a larger development than usual, and the Insects are as skilful in running as if they possessed eyes. Anophthalmus is closely related to our British genus Trechus, the species of which are very much given to living in deep crevices in the earth, or under large stones, and have some of them very small eyes. In addition to these cavernicolous Anophthalmus, other blind Carabidae have been discovered during recent years in various parts of the world, where they live under great stones deeply embedded in the earth; these blind lapidicolous Carabidae are of extremely minute size and of most sluggish habits; the situations in which they are found suggest that many successive generations are probably passed under the same stone. Not a single specimen has ever been found above ground. The minute Carabids of the genus Aëpus, that pass a large part of their lives under stones below high-water mark (emerging only when the tide uncovers them), on the borders of the English Channel and elsewhere, are very closely allied to these blind Insects, and have themselves only very small eyes, which, moreover, according to Hammond and Miall, are covered in larger part by a peculiar shield.[[87]] A few Carabidae, of the genera Glyptus and Orthogonius, are believed to live in the nests of Termites. Savage found the larva of G. sculptilis in the nests of Termes bellicosus; it has been described by Horn, and is said to bear so great a resemblance to young queens of the Termites as to have been mistaken for them.[[88]] Mr. Haviland found Rhopalomelus angusticollis in Termites' nests in South Africa. Péringuey states that it emits a very strong and disagreeable odour. It is probable that it preys on the Termites, and this also is believed to be the habit of the Ceylonese Helluodes taprobanae. Some species of the Mediterranean genus Siagona stridulate by means of a file on the under surface of the prothorax, rubbed by a striate area, adapted in form, on the anterior femora.
A valuable memoir on the classification of this important family is due to the late Dr. G. H. Horn;[[89]] he arranges Carabidae in three sub-families; we think it necessary to add a fourth for Mormolyce:
1. Middle coxal cavities enclosed externally by the junction of the meso- and meta-sternum; neither epimeron nor episternum attaining the cavity.
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 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.
