. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. PYCNOGONIDA. characteristic in contradistinction to the others, or when one or more pairs have disappeared, so that sExtrem. IV» is to be understood, now as the first, now as the second, third, or fourth pair of the preserved hmbs of the imago. The greatest drawback by Dohrn's way of designation is to me that it does not at all agree with the developmental history, the embryonal legs (fig. 2 b, c) not being included; and although they are not to be regarded as the predecessors of the two f
. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. PYCNOGONIDA. characteristic in contradistinction to the others, or when one or more pairs have disappeared, so that sExtrem. IV» is to be understood, now as the first, now as the second, third, or fourth pair of the preserved hmbs of the imago. The greatest drawback by Dohrn's way of designation is to me that it does not at all agree with the developmental history, the embryonal legs (fig. 2 b, c) not being included; and although they are not to be regarded as the predecessors of the two foremost pairs of ambulatory legs (Kroyer), they are neither the predecessors of the second and third typical pairs of limbs of the imago, the imaginal fore-limbs, or of the palpi and the ovigerous legs. I hope that it will appear from my examination of the larval development that these two pairs of limbs are not predecessors of, or identical with, the embryonal legs, to which examination the reader is referred. Now, if the embryonal legs are neither identical with the two first pairs of ambulatory legs (Krover), nor with the palpi and ovigerous legs (Dohrn's Extrem. II and III), there will be typically 9, and not 7, pairs of limbs, as supposed by Dohrn and all naturalists, excepting Semper, Pycnog. und Larvenf., 1874 (who has 8 pairs). Even if it be supposed that the embryonal legs are peculiar limbs, it would, of course, be possible to use the appellation of Dohrn, the list of limbs then only being increased from VII to IX; but on the other hand it would be very untoward to be always obliged to subtract several, sometimes more than the half, from the number, which is got by adding the embry-. Fig. I. Nymphon Stroemii. (J f. C. o. cl. apo. c^. a. C4. sc. pel. chf. s. ch. plm. dim. dm. pa. cx^. cx^. cxi. f. /a\ ta^. u. no. pip. po. plr. glov. Proboscis (rostrum). First segment of trunk (segnientum corporis primum). Oculiferous tubercle (tuber oculare). Neck (coUum). Lateral pro
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Keywords: ., bookcentury1800, bookdecade1890, booksu, booksubjectarcticregions
