. Smithsonian miscellaneous collections. in is occupied by a membrane only upto the point where the radial vein is bent forward and structurallyreplaces the costa. The base of the costa is produced into the so-calledcostal head (fig. 30, CoH). It consists of two parts, the costal condyle(fig. 30, a), and the costal pocket (b). The former articulates withthe clavicle process of the metaepisternum (fig. 17, di). From thebase of the costal condyle a pocket stretches to the subcosta. At aboutthe center of the pocket a projection of the subcostal head, the sub- 54 SMITHSONIAN MISCELLANEOUS COLLECTI
. Smithsonian miscellaneous collections. in is occupied by a membrane only upto the point where the radial vein is bent forward and structurallyreplaces the costa. The base of the costa is produced into the so-calledcostal head (fig. 30, CoH). It consists of two parts, the costal condyle(fig. 30, a), and the costal pocket (b). The former articulates withthe clavicle process of the metaepisternum (fig. 17, di). From thebase of the costal condyle a pocket stretches to the subcosta. At aboutthe center of the pocket a projection of the subcostal head, the sub- 54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 costal hinge (lig. 30, c). is attached by tendons giving the motion ofa hinge joint. This attachment enables the subcostal head to move inthe pocket. Siihcosta.—The subcosta (figs. 3, Sco, 17, Sc, 30, Sco) consists ofa chitinous band extending apically as far as the costa and strengthenedby two ridges of dense chitin. The basal part, or subcostal head (, ScoH), as it was called by Hopkins, is anteriorly formed into a. Fig. 30.—Gnathotrichtts rctusus Lee.: Basal area of the wing, wing articulation. Co, costal vein; CoH, costal head; Cii, cubital vein; Me, medial vein; Sco, subcostalvein; ScoH, subcostal head; ax, axillary plates; a, costal condyle; b, costal pocket; c,subcostal hinse; d, subcostal labruni; e, condyle of first axillary; /, subcostal fossa; g,membranous fold connecting Me and axt; h, membranous fold connecting Me and Cu; i,membranous fold connecting Cii and axs; j, epicondyle of ax^; k, scapula arm; /, axillaryhorn; m. axilla; n, anterior process of ax-\ o, articulatory margin; p, scapular hook ofprescutum; q, apical margin; r, lateral groove; s. axillary tendon; t, «, lateral emarginations;t, posterior part, or handle; w, anterior part, or blade. projection which is composed of a circular band of chitin (fig. 30, c),articulating with the costal pocket. The posterior part forms a fossa,the subcostal fossa (f), which articulates with the cond
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Keywords: ., bookauthorsm, bookcentury1800, bookdecade1860, booksubjectscience
