Lec. Both of these species are from Lake Superior. Syntomium is represented in Russian America. The other genera are found on both sides of the continent.

Tribe VII.-OMALINI.

In this tribe the prothoracic spiracles are concealed by the inflexed portion of the pronotum; the prosternum behind the coxæ is membranous; the anterior coxæ are conical and prominent, the posterior ones transverse; the hind trochanters are on the internal margin of the thighs; the tarsi are 5-jointed; the palpi are filiform, except in Coryphium, where they are subulate; the head is furnished behind with two simple lenses or ocelli, which are usually placed on a line joining the posterior margins of the eyes. The antennæ are inserted under the lateral margins of the front. The second ventral segment is carinate at the base.

The genera are numerous, and are best distinguished by the parts of the mouth, which are not to be examined without dissection. For a full account of the differences between the genera the student must refer to the second volume of the Insecten Deutschlands, by Kraatz. The following characters may enable him to recognize those of our fauna :—

A. Maxillary palpi with the last joint long or moderate; posterior tarsi with joints 1-4 of unequal length; elytra moderate;

Mandibles toothed; tibiæ not spinous; hind tarsi with the first joint
elongated;

Maxillary palpi with the last joint not elongated. ANTHOPHAGUS.
Maxillary palpi with the last joint three times as long as the pre-

ceding.

Mandibles not toothed;

LESTEVA.

Tibiæ spinous; hind tarsi with the first joint elongated. ACIDOTA.
Tibiæ not spinous; hind tarsi with the first and second joints equal;
Lobes of the maxillæ elongate, corneous.
Lobes of the maxillæ membranous.

OLOPHRUM. LATHRIMÆUM.

Tibiæ spinous; hind tarsi with the first and second joints elongated,

not equal, first very long.

AMPHICHROUM.

Tibiæ not spinous; hind tarsi with the first joint slightly elongated;

one mandible toothed.

PORRHODITES.
CORYPHIUM.

B. Maxillary palpi with the last joint small, subulate.

C. Maxillary palpi with the last joint long; hind tarsi with the joints 1-4

Lathrium Lec. is not sufficiently distinct from Olophrum, and the species L. convexicolle from Lake Superior greatly resembles O. convexum Mäklin from Russian America.

Tribe VIII.-PROTEININI.

This tribe contains a very small number of species, approaching closely to the preceding tribe, but differing by the prosternum being corneous behind the coxæ, and by the head having no ocellus in our genera, and but one in certain foreign genera. The antennæ are inserted under the sides of the front; the anterior coxæ are transverse, subconical, and somewhat prominent; the hind coxæ are transverse; the hind trochanters are at the inner margin of the thighs; the tarsi are 5-jointed. The species live in fungi and under bark.

Our two genera without frontal ocellus are distinguished by the form of the antennæ.

Antennæ with the joints 9-11 larger.

Antennæ with the eleventh joint only larger.

PROTEINUS. MEGARTHRUS.

The latter genus is further remarkable for having the sides of the thorax frequently with an angle behind the middle; the thorax is also always channelled.

Tribe IX.-PHLŒOCHARINI.

This tribe consists also of a very small number of species, of slender, depressed form, and is represented in our fauna only by the genus Olisthærus, found in the northern regions, from Canada to Russian America, under bark.

The prothoracic spiracles are covered; the thorax behind the anterior coxæ is membranous; the latter are conical and prominent, and the hind coxæ are transverse; the hind trochanters are on the internal margin of the thighs; the tarsi are 5-jointed.

The antennæ are inserted under the sides of the front, straight, 11-jointed, scarcely thickened externally. The second ventral segment is longitudinally elevated at the middle.

It will thus be seen that this tribe differs from Omalini by the absence of ocelli, and from Tachyporini only by the prothoracic spiracles being covered.

In Olistharus the anterior tarsi are not dilated, and the maxillary palpi are filiform.

Sub-Family II.-PIESTIDAE.

Insects having a slender and frequently very depressed form, living under bark. The prothoracic spiracles are covered, and the whole prosternum is corneous, and in some genera separates the anterior coxæ so that the coxal cavities become entire. The antennæ are situated under the sides of the front, straight, slightly thickened externally. The second ventral segment is longitudinally elevated at the middle.

In this sub-family the present family shows its strongest tendency towards the collective Clavicorn families in Cucujida; in the next we will find this tendency towards another member of the same series. Our genera are as follows:

A. Anterior coxæ contiguous;

Abdomen margined, tarsi 5-jointed;

Anterior tibiæ spinous, abdomen broadly margined;
Maxille with the outer lobe dilated; (elytra striate).

PROGNATHA.

Maxilla with the outer lobe not dilated; (elytra punctate).

HYPOTELUS.

Anterior tibiæ not spinous, abdomen narrowly margined.

ISOMALUS.

Abdomen not margined, tarsi 3-jointed; (thorax and elytra costate).

GLYPTOMA.

B. Anterior coxæ separated, abdomen not margined, tarsi 5-jointed.

LISPINUS.

Sub-Family III.-MICROPEPLIDAE.

This sub-family consists of a single genus, containing small subquadrate species, having the thorax, elytra, and abdomen ornamented with acutely elevated ribs; the antennæ are inserted under the sides of the front, 9-jointed, and terminate in a small club received into cavities on the under surface of the prothorax; the prosternum is entirely corneous. The anterior coxæ are transverse, not prominent, the hind ones distant, rounded; the tarsi are 3-jointed. The second ventral segment is broadly dilated at the middle, and separates the hind coxæ.

This sub-family thus completes the approach of the Staphylinide towards the Clavicorn series in Histeridæ.

FAM. XI.-HISTERIDAE.

Mentum corneous, sometimes large and covering the base of the maxillæ, flat or slightly concave, subquadrate, sometimes emarginate or tridentate in front; ligula almost concealed behind the mentum; palpi 3 jointed, cylindrical.

Maxilla with two ciliated lobes, the internal one much smaller; palpi 4-jointed, cylindrical.

Antennæ geniculate, capable of being retracted, short, in the second sub-family with the first joint thick, but in the first with the first joint long, the eighth and following ones forming a compact, annulated, rounded, or (rarely) triangular club.

Prothorax closely applied to the elytra; side pieces not distinct;* in most of the genera with two cavities to receive the club of the antennæ; prosternum frequently lobed in front, produced behind, articulating with the mesosternum; coxal cavities open behind.

Mesosternum separating widely the middle coxæ; side pieces large, not divided, sometimes visible from above.

Metasternum very large, almost connate with the mesosternum anteriorly; episterna sometimes narrow, sometimes broad, occasionally curved; epimera broad, large, separated by a fine suture, which is sometimes effaced.

Elytra truncate behind, leaving two segments of the abdomen uncovered; scutellum small in the first sub-family, entire in the second.

Abdomen with five free ventral segments, the first very large, the fifth very short, closely applied to the last dorsal segment, which is triangular and deflexed.

Anterior coxæ transverse and not prominent in the first sub-family, globose in the second; middle and posterior coxæ widely separated, not prominent, rounded, or rather subquadrate, the latter not extending to the sides of the body.

Legs short, retractile; tibiæ compressed, anterior ones usually toothed, posterior sometimes toothed; spurs distinct, those of the anterior pair very unequal. Tarsi slender, short, 5-jointed in the first sub-family (except in Acritus, where the posterior ones are 4-jointed), 4-jointed in the second subfamily; claws (in all of our genera) two, simple; anterior tarsi usually received in grooves on the anterior face of the tibiæ.

* In some species there is an elevated line, simulating a suture.

A very well defined family of insects, moderately numerous, nearly all of a shining black color, with the elytra variously sculptured with striæ; some few species of Hister and Saprinus have the elytra marked with red, and a few of the latter genus are metallic in color. The form of body is variable; those of the first group are oblong and flat, with prominent mandibles; the others are round, oblong, oval, globose, some depressed and some convex. The species live under bark of trees, in excrements, and in carcasses. When touched, the insects retract the antennæ and feet, appearing as if dead.

The metasternum is marked by two distant lines diverging posteriorly, and the first segment of the abdomen with two similar

ones.

The genera in this family appear to me to have been multiplied unnecessarily by later authors. I accordingly have made, when necessary, two tables, one of the genera as understood in the great monograph of Marseul, the other of those which appear to me to be entitled to real generic distinction.

The family may be divided into two natural sub-families, as follows:

Antennæ with the first joint very long; elytra truncate.
Antenna with the first joint very thick; elytra entire.

HISTERIDA. MURMIDIIDA.

Sub-Family I.-HISTERIDAE (genuini).

The geniculate antennæ, with the first joint elongated, and the truncate elytra permitting the last two dorsal segments of the abdomen to be visible, sufficiently distinguish this sub-family from the next.

It is divided, following the example of Lacordaire, into two very natural tribes, according to the position of the head in repose:

Head porrected.

Head retracted, bent downwards.

Tribe I.-HOLOLEPTINI.

HOLOLEPTINI.
HISTRINI.

Body very much depressed above and below; head extended, with long, prominent mandibles; antennæ inserted under the sides of the front, the club not received in definite prosternal cavities;