. Occasional papers of the California Academy of Sciences. e had almost immediate sig-nificance in the survival of the possessor. The basal tarsal segment (Fig. 18) is elongate-oval. In alate males it is narrower and more cylindri-cal in cross-section than in females, nymphs andnymphoid apterous males. In females and nymphsthe segment is almost triangular in cross-section dueto slant of the inner-dorsal surface. The outer side isalmost vertical. The inner-dorsal surface is almostentirely submembranous, finely reticulate in textureand almost lacks setae. A medial, longitudinal de-pression which
. Occasional papers of the California Academy of Sciences. e had almost immediate sig-nificance in the survival of the possessor. The basal tarsal segment (Fig. 18) is elongate-oval. In alate males it is narrower and more cylindri-cal in cross-section than in females, nymphs andnymphoid apterous males. In females and nymphsthe segment is almost triangular in cross-section dueto slant of the inner-dorsal surface. The outer side isalmost vertical. The inner-dorsal surface is almostentirely submembranous, finely reticulate in textureand almost lacks setae. A medial, longitudinal de-pression which extends the length of the surface grad-ually becomes stronger terminally. The areaimmediately inward of this depression often surfaces adjacent to this membrane are darkerand clothed with moderately long setae of the usualtype. The ventral, or plantar, surface of the basal seg-ment (Fig. 20A) is entirely membranous, pale, oftenpinkish in color, and densely covered with short. ROSS: EMBIA, BI0SYSTEN4AT1CS OF THE ORDER EMBIIDINA. PART 1 23. Figure 19. A. Hypothetical origin of silk gland. B. Defini-tive structure of a single gland and its ejector. C. Glandularcontent of foretarsus of a female. acutely-tapered microspicules which may functionas combs. Silk-ejectors on the outer edge arise with-in small, circular areas lacking such ejectors are characterized by a lack of basal sock-ets and are thin walled, fragile and whitish— condi-tions apparently associated with their hollow are variable in form and length but are straightexcept for occasional abrupt curvature of their com-plex apices (Fig. 20B, C). Along the lateral margins of the plantar surfacethe microspicules are much shorter and the bare spotsfrom which the ejectors arise are more arising from these lateral borders appear tobe much longer than elsewhere and probably are themost important silk-strand ejectors. The mid-segment of the foretarsus is a small
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectscience, bookyear1890
