Oblique: any direction between perpendicular and horizontal. Oblique vein: in Odonata; an apparent cross-vein situated between M2 and Rs, distal to the level of the nodus and inclined obliquely, from its front end, backward and outward; in reality the basal part of Rs. Obliterate: nearly washed out; indistinct. Oblong: longer than broad. Obovate: inversely egg-shaped; the narrow end downward. Obpyriform: inversely pearshaped. Obscure: not readily seen: not well defined. Obsite-us: a surface covered with equal scales or other bodies. Obsolete: nearly or entirely lost: inconspicuous. Obtect: wrapped in a hard covering. Obtected: applied to pupae when they are covered with a chitinous case which confines and conceals all appendages, though their outlines may be marked on the surface: see free, and coarctate. Obtuse: not pointed: an angle greater than a right angle: opposed to acute. Obtuse-angulate: two markings or margins meeting so as to form an obtuse angle. Obtusilingues: short-tongued bees with the tip obtuse or bifid: see acutilingues. Occipital foramen: the opening in the occiput, opposed to a similar opening in the prothorax: = foramen magnum. Occipital margin: in Mallophaga, the posterior margin of the head. Occipito-orbital bristles: in Diptera; situated on posterior orbit of eye. Occiput: that part of the head behind the vertex: in Diptera, the whole posterior surface of the head: in bees, the space between the vertex and the neck. Occlusor: applied to muscles which close an opening; e.g. spiracles. Occult -us: hidden; concealed from superficial view. Ocellar bristles: in Diptera, are situated close to the ocelli, usually directed forward: often absent. Ocellar ribband: a crescent-shaped, smooth thin belt across the eye region in butterfly chrysalids. Ocellar triangle: a triangle, indicated by grooves or depressions, on which the ocelli are situated; Diptera. Ocellate: eye-like in appearance: in Lepidoptera, spots on the wings, bordered by a colored iris or ring, and usually with a pupil. Ocelli: plural of ocellus; q.v.; = stemmata. Ocelligerous: supplied with, or bearing ocelli. Ocellus: a simple eye, consisting of a single convex or bead-like lens, which conveys an image to a retina. Ocelli occur in larvae and, singly or in small groups, in adults: the compound eyes are made up of numerous ocelli. Ochraceous: yellow with a slight tinge of brown [pale cadmium yellow and brown ochre]. Ochraeus -eus: = ochraceous. Ochro-leucus: dilute ochraceous. Ocular emargination: in Mallophaga, a lateral emargination of the head in which the eye is received posteriorly. Ocular fleck: in Mallophaga, a small, intensely black spot of pigment in the eyes. Ocular fringe: in Mallophaga, closely set small hair on posterior half of ocular emargination, sometimes extending on temporal margin. Ocular lobes: of brain = procerebrum; q.v. Ocular sclerite: the first or protocerebral segment of the head.