. Occasional papers of the California Academy of Sciences. ? apophyseal pit 1 preolor suture--ianapleural cleft -- preepisternum - episternum- apophyseal pit 2- trochantin ventropleurite - — poststernum - prealar suture- furcasternum.^ preepisternum -. episternum . - -ventropleurite - apophyseal pit 3 - trochontin coxa 3 abdominal sternum 1. A B Figure 15. Meso- and metathorax. ventral aspect of A. Adult female and B. Adult male. Oligowma nigra Hagen. Their present simple juvenile thoracic structure stronglycontrasts with ancestral complexity retained in the tho-rax of alate males. Thoracic si
. Occasional papers of the California Academy of Sciences. ? apophyseal pit 1 preolor suture--ianapleural cleft -- preepisternum - episternum- apophyseal pit 2- trochantin ventropleurite - — poststernum - prealar suture- furcasternum.^ preepisternum -. episternum . - -ventropleurite - apophyseal pit 3 - trochontin coxa 3 abdominal sternum 1. A B Figure 15. Meso- and metathorax. ventral aspect of A. Adult female and B. Adult male. Oligowma nigra Hagen. Their present simple juvenile thoracic structure stronglycontrasts with ancestral complexity retained in the tho-rax of alate males. Thoracic simplicity in adult femalesobviously results from neoteny for its sclerotization isnearly identical to that of immature stages of females,and the second instar of males destined to developwings. Some difficulties in interpretation can perhapsbe attributed to the fact that most sclerites are rathersoft and are seldom fused along sutural lines. Thiswould appear to make possible distention of the midg-ut and more supple body movement—the latter a de-cided advantage in gallery life. The apterous condition of adult females, and the same tendency in males ofsome species, is undoubtedly an adaptation for life insilk galleries, as will be fully treated in the section deal-ing with wings. The meso- and metathoracic scuta of females aresimple,
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectscience, bookyear1890
