. Bulletin - New York State Museum. Science. 20 NEW YORK STATE MUSEUM or three filiform appendages which terminate the abdomen are here called caudal setae. The tarsi are typically five-jointed in the adult, though one or two basal joints show a marked tendency to fuse with the end of the tibia, and the last joint bears two claws of vari- able form () ; in the nymph the tarsus is one- jointed and bears a single claw (Plate 6, fig. 7 and 8). The mouth parts in the adult are atrophied and functionless, while in the nymph they are highly developed. But one feature of them needs mention here,
. Bulletin - New York State Museum. Science. 20 NEW YORK STATE MUSEUM or three filiform appendages which terminate the abdomen are here called caudal setae. The tarsi are typically five-jointed in the adult, though one or two basal joints show a marked tendency to fuse with the end of the tibia, and the last joint bears two claws of vari- able form () ; in the nymph the tarsus is one- jointed and bears a single claw (Plate 6, fig. 7 and 8). The mouth parts in the adult are atrophied and functionless, while in the nymph they are highly developed. But one feature of them needs mention here, however; that is the armature of the mandible. By comparing , , and , , it will be seen. Fig. 1 Venation of the wings of S i p h 1 u r u s; lettering explained in text that each mandible bears on its inner side a broad more or less corrugated molar surface^ and at its antero-lateral angle several variable canines.^ To the venation of the wings the student who aspires to an acquaintance with mayflies would do well to pay special heed. This is of chief importance because 1) the venation is perfectly definite and easily observed; 2) it suffers least distortion in pre- served specimens; 3) it remains the same through the different developmental stages, and 4) the wdngs are better retained than the other appendages, and progress is better in using a key if the structures mentioned in it have not been lost. The main features 1 Following the terminology of Vayssiere for these parts. Organisation des larves des Ephem^rines: Ann. Sci. Nat. (6) 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
