File:Natural science- a monthly review of scientific progress (1895) (14781036731).jpg

Identifier: naturalsciencemo61895lond (find matches)
Title: Natural science: a monthly review of scientific progress
Year: 1895 (1890s)
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Publisher: London (etc.), Macmillan and Company (etc.)
Contributing Library: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library
Digitizing Sponsor: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library

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hood in middle line... ... ... 10-5 ,, Breadth of body across middle of eyes ... 15 ,, The surface of the hood was perfectly white and unpigmented.The branchiae of opposite sides were in close apposition in themedian line, and, curiously enough, the larger posterior pair extendedforwards far into the interior of the funnel. The shell was perforated at the umbilicus, as it is throughout lifein N. umbilicatus. 5.—Relations of male and female (N. pompilius).— Out of sixty-sevenindividuals, fifty-one were male and sixteen female, so that the i895- IN THE HOME OF THE NA UTIL US. 411 statement in Pelseneers recent Introduction a letude desMollusques, that hyperpolygynie occurs with the Nautilus,requires modification. Most of the females that I have obtained have been immature,whereas many of the males have been mature, and have hadspermatophores in the Needhamian vesicle and motile spermatozoain the testis, and, in rarer instances, I have found a spermatophore in Extreme of Difference.
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Minimum of Difference.Fig. 1. Secondary sexual characters in shells of Nautilus pompilius. the angle formed by the buccal mass with the dorsal hood, attached tothe innermost tentacles of the inner lobes of the cephalic tentacularsystem, as first described by Van der Hoeven. There are reasons forthinking with Van der Hoeven that the spermatophore remains herefor a long time. Van der Hoeven and Keferstein describe a difference in thedimensions of the hood in male and female. I have made a large 2 g 2 4i2 NATURAL SCIENCE. June, number of measurements of the shells to ascertain if there was anyconstant difference between male and female. The male shellsaverage larger than the females, but there is an astonishing amountof variation in the proportional dimensions of the shells of both sexes,into which, however, I need not now enter. The essential differencesbetween the male and female shells will be seen clearly in theaccompanying figures (Fig. i), which are pen-and-ink tracings fromphotogr

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