. Bulletin - New York State Museum. Science. AQUATIC INSECTS IN NEW YORK STATE 239 middle legs; the mentum is less than a third longer than wide; median lobe spinulose on its prominent free border; no mental setae; lateral setae one to four; lateral lobe short, lialf as wide as long, with short, stout, movable hook and small end hook separated by a more or less distinct notch from the inner margin, and with one or more smaller teeth on the distal end above the end hook. Prothorax pointed anteriorly and fitting the rear emargina- tion of the head. Mesothorax and metathorax much thicker,. Fig. 9
. Bulletin - New York State Museum. Science. AQUATIC INSECTS IN NEW YORK STATE 239 middle legs; the mentum is less than a third longer than wide; median lobe spinulose on its prominent free border; no mental setae; lateral setae one to four; lateral lobe short, lialf as wide as long, with short, stout, movable hook and small end hook separated by a more or less distinct notch from the inner margin, and with one or more smaller teeth on the distal end above the end hook. Prothorax pointed anteriorly and fitting the rear emargina- tion of the head. Mesothorax and metathorax much thicker,. Fig. 9 Outline of head of nymph ofArgia apicalis with the wings borne at a considerable elevation. Legs short, usually banded transversely, and bearing spines as well as hairs. Abdomen stout, somewhat tapering, and with its segments -decreasing in length to the ninth, the tenth again a little longer. Gills oblong about half as long as wide, obtuse at apex and generally with paler apical markings. Among alcoholic specimens frequently, and among fresh specimens occasion- ally, the gills are absent, being easily broken off. If their loss occur early in nymphal life, they are regenerated, and it is no uncommon thing to find a specimen with one, two or three of the gill plates of smaller size than the normal. The loss of the gills seems not to affect seriously the respiration of the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original New York State Museum; New York State Museum. Albany : New York State Education Dept
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectscience, bookyear1887
