. Biological series. Biology. Walker: North American Species of Aeshna ii a concave chitinous process arising from the floor of the geni- tal fossa; and on each side of the sheath, generally concealed by the overlapping tergal margins, is one of the posterior hamuli, two simple chitinous processes of the walls of the genital fossa bearing upon their apices a number of long hairs. In front of the posterior hamuli, and in some species (none North American) partly concealed by the hairs of the latter, are the much larger and more complicated anterior hamuli. Each anterior hamulus consists of a br
. Biological series. Biology. Walker: North American Species of Aeshna ii a concave chitinous process arising from the floor of the geni- tal fossa; and on each side of the sheath, generally concealed by the overlapping tergal margins, is one of the posterior hamuli, two simple chitinous processes of the walls of the genital fossa bearing upon their apices a number of long hairs. In front of the posterior hamuli, and in some species (none North American) partly concealed by the hairs of the latter, are the much larger and more complicated anterior hamuli. Each anterior hamulus consists of a broad, some- what triangular thickening of the wall of the genital fossa and a folded, strongly chitinized mesially concave process, arising from its sloping mesial surface. The two concave processes of opposite hamuli form a pair of claspers for the ovipositor during copulation and their efficiency as such is increased by the presence, in each concavity, of a small ele- vation thickly covered with spinules, (fig. 2, t). For descriptive purposes each clasper may be divided into two parts, the hamular process and the hamular fold. The ham- ular process (fig. 2, hp) is a freely projecting structure, the most anteriorly and ventrally situated part of the clasper. The two processes together form the floor of the passage for the ovipositor. The hamular folds (fig. 2, hf), so called from their folded form, are the more posterior and dorsal part of the clasper and close the passage above and behind. Generally the hamular process and fold are not sharply marked off from one another, the free margin of the one pass- ing insensibly into that of the other; but in some cases the. Fig. a—Anterior lamina and anterior hamuli of (A) Aeshna interrupta (B) We/wwrea L: a/ anterior lamina ; tm, tergal margin of segment a ; 5^ spine of anterior lamina ; hp hamula process ; t spinulose tubercle ; b basal part of hamulus ; h f hamular Please note that these images are extracted from sca
Size: 2477px × 1009px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectbiology, bookyear1898
