apical angle


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apical angle

[′ap·i·kəl ′aŋ·gəl]
(mechanics)
The angle between the tangents to the curve outlining the contour of a projectile at its tip.
(optics)
The dihedral angle between the refracting faces of a prism. Also known as refracting angle.
References in periodicals archive ?
the apical margin of the protibia of the female has a subcarinate ridge ending in an elongate, subacute uncus projecting posteriad, and has an acute mucro on the inner apical angle, partly concealed by 2 clusters of coarse setal brushes anterior and posterior to the mucro.
Forewing light yellow, costal margin tinged slightly with grey, pagina with some irregular brown transverse lines, strongest one from inner side of apical angle to middle of posterior margin, dark brown oblique line starting below apical angle to metagonia, apical angle slightly round, outer margin curved, fringe scales grayish-yellow.
9) (Pseudavakubia) 10 2 Shell with distinctly acuminate apex and tapering spire (apical angle generally < 120[degrees], spire angle <60[degrees]) 3 -- Shell apex more rounded, spire aspect less tapering (apical angle at least 120[degrees], spire angle >62[degrees]) 4 3 Adult shell >5 mm, elongate, apex strongly acuminate, spire appearance less tapering; apical angle <100[degrees].
Small shell of 10 to 11 whorls with gradually tapering spire; whorls evenly rounded; sutures impressed; one fine, spiral thread just below suture and one fine thread just above suture; three larger, evenly spaced threads on central portion of whorl; interspaces wider than threads; apical angle of 26 degrees; aperture and slit not observed.
The species name is derived from the Latin words "rotundatus", referring to the forewing with a black round spot at the apical angle.
Marginal impression shallow, narrow near apical angle, broadly widened to basal angles.
Parameres short, dorsocaudally directed, twice wider at basal half, narrower and subparallel sided at the apical half; in caudal view, apical half with profile rectangular with acute inner apical angle (Fig.
Genae mostly dark brown but apical small part yellow; in posterior view, process of anal segment of male relatively long and stout, sinuous, situated on left side of ventral margin; outer apical angle of genital styles forked 4
Forewings with acute apical angle, outer margin approximately straight, oblique, posterior margin sinuate, with irregular markings at apical half (Figs.
Macropterous, extending beyond apex of last abdominal segment; costal margin emarginated, shallowly concave near midpoint; apical margin long, oblique, almost straight; apical angle subacute to truncate.
Structure: body oblong, parallel-sided; head with vertex slightly convex; eyes simple, barely pedunculate; buccula low, short, scarcely extended backward as far as the antenniferous tubercles, and apically rounded; rostrum reaching middle third of metasternum; pronotum with collar wide; frontal angles obtuse, rounded; anterolateral margins narrowly but distinctly carinate; humeral angles rounded, not exposed; fore femur with two subapical spines; middle and hind femora unarmed; macropterous, hemelytral membrane extending beyond the apex of last abdominal segment; costal margin slightly emarginate; apical margin straight; apical angle subacute; abdomen parallel, not dilated.