Somewhat less than 100 species of this family are at present known; the great majority are found in the Mediterranean region, but there are several in North America. As a single species is known from Mexico and another from Japan, it is probable that the family may prove to have a wider geographical extension than at present appears to be the case.
Fam. II. Oryssidae.
The median plate behind the metanotum entire, not divided in the middle; antennae inserted below the eyes immediately above the mandibles, under a sharp edge.
This family consists of the genus Oryssus, and includes only about twenty species, but is nevertheless very widely distributed over the world. They are very rare Insects, and little is known as to their habits; one species, O. abietinus, was formerly found in England. Should any one be so fortunate as to meet with it, he can scarcely fail to recognise it on noticing the peculiar situation of the base of the antennae. In this respect the Chrysididae somewhat resemble Oryssus, but in that group of Hymenoptera the hind body or abdomen is remarkably mobile, so that the Insects can coil themselves up by bending at this joint; whereas in Oryssus the hind body is very closely amalgamated with the thorax—more so, in fact, than in any other Hymenopterous Insect—and has no power of independent movement.
Fig. 341.—Oryssus sayi. North America. A, The female Insect; B, head seen from the front.
Oryssus abietinus very closely resembles C. sayi (Fig. 341); it has indeed been recently suggested by Mr. Harrington that the two supposed species may really be identical.
Fam. III. Siricidae or Uroceridae.
Pronotum closely connected with the mesonotum, perpendicular in front; the anterior lobe of the latter not separated by the lateral lobes from the posterior lobe: the median plate (behind the metathorax) is divided longitudinally along the middle. The female is provided at the extremity of the body with an elongate, cylindrical boring instrument. The larvae live in the wood of trees.
