. Smithsonian miscellaneous collections. is that of the mesosternum, and the suture of thetransverse sternal ridge (^) is here also coincident with the transversemargin of the sternal notch; but the suture does not extend laterad ofthe apophyses (sa, sa), and the lateral sternellar lobes are, therefore,4 50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 not set off by sutures as in the mesosternum. The small triangularplates (t, t) bordering the coxal cavities appear to be subdivisions ofthe sternellar lobes rather than subcoxal laterosternal pieces, since theventral arms of the pleurites in th
. Smithsonian miscellaneous collections. is that of the mesosternum, and the suture of thetransverse sternal ridge (^) is here also coincident with the transversemargin of the sternal notch; but the suture does not extend laterad ofthe apophyses (sa, sa), and the lateral sternellar lobes are, therefore,4 50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 not set off by sutures as in the mesosternum. The small triangularplates (t, t) bordering the coxal cavities appear to be subdivisions ofthe sternellar lobes rather than subcoxal laterosternal pieces, since theventral arms of the pleurites in the nymph (fig. 27 A, Ls) form onlythe membranous folds beneath the coxal cavities in the metathorax. There is no spina associated with the metasternum. Crampton(1918) says the spinal pit has disappeared from the metasternum, buthe gives no evidence of its former existence. As we have seen, theintersternal sclerotization between the metasternum and the first ab-dominal sternum remains as an integral part of the latter, or disappears Eps^. o^ 2Spn Fig. 31.—Inner surface of ventral pleuro-sternal region of mesothorax. Bs, basisternum; Cxd, coxal cavity; Epm, epimeron; Eps, episternum;Isg, intersegmental groove; /, ridge of prepectal suture; k, furcal ridge; PIA,pleural arm; PIR, pleural ridge; PIS, pleural suture; Ppct, prepectus; ^3, an-terior part of metasternum; SA, sternal apophysis; SI, sternellum; 2Spn, secondspina, united with furcal ridge of mesosternum. when the first abdominal sternum becomes rudimentary. In Dissosteirathe ventral muscles of the first abdominal segment (fig. 35, IS) areattached anteriorly on a weakly developed ridge (Ac) which crossesthe first abdominal sternum between the angles of the sternellar lobesof the metasternum. The line of this ridge appears externally as afaint transverse suture (fig. 30 A, D, acs). The ridge (fig. 35, Ac),therefore, is the antecosta of the first abdominal sternum, and therepresentative of the spinae of the prothoracic and m
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Keywords: ., bookauthorsm, bookcentury1800, bookdecade1860, booksubjectscience
