Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
— the small size of the figure, the method of reproduction, etc. — 3) it seemed exeeedingly
important to give a vérification of the figures by means of the text.
With regard to the description of the s hell we must note:
Ail shell measurements are taken by means of an ocular micrometer. Like most preceding
authors I have, when measuring the length of the shell, included any processes that were
present, e. g. the rostrum, spines, etc. In his measurements of H a 1 o cy p rids and Cypr
i-dinids G. H. FOWLER, 1909, measured „parallel to the dorsal border from the most
prominent part of the anterior border, ventral to the niche for the second antenna“ to the most
projecting part of the posterior border, leaving out of account any spines that might exist.
This method of measuring was to give ,,a real measurement of the shell, which is comparable
in different species“ (loc. cit. p. 222). As I never had any need of any such „real“ values,
I have, as stated above, employed the method used by other investigators.
G. W. MÜLLER writes, 1894, p. 9, as follows: „Die meisten Untersuchungen an der Schale
können mit Erfolg nur an isolierten Schalen vorgenommen werden, besonders sollten
Profilzeichnungen nur nach ihnen gemacht werden . . . .“ This principle has been applied to as
great an extent as possible in the present work. Only in cases where it was impossible, on
account of the soft condition of the shell, to separate the two valves without destroving the
form has the profile been drawn from the whole shell. ln the latter case the body was almost
always first removed from the shell. „Man ist dann leichter im Stande, das Thier in die
Profillage zu bringen“ (G. W. MÜLLER, 1894, p. 10).
During the drawing of the profile the shell is most conveniently fixed, if it is drawn
whole, by means of gelatinous glycérine.
G. W. MÜLLER writes as follows in his work of 1894, p. 9, with regard to the shell: „Man
untersuche, wenn auch vorwiegend, so doch nicht ausschließlich in Canadabalsam oder Nelkenöl,
sondern auch in Glycerin, eventuell auch in Wasser oder Alkohol, da häufig Einzelheiten der
Sculptur in Canadabalsam vollständig verloren gehen.“ To this it may be objected that it is
absolutely necessary to investigate and reproduce sculptured shells in a dry condition and
in reflected light. If the shell is investigated in a liquid we may easilv obtain a mistaken
idea of the sculpture whether we use reflected or transmitted light. — The reproduction of the
sculpture as it appears in transmitted fight is of course inconvénient, because by this the
identification of fossil forms is rendered much more difficult.
The figures of the shells ought to be made comparativelv large and as similar in details
as possible; generalized and minute figures, such as those of G. S. BRADY, are of little use to
us; sculptured shells ought to be reproduced by means of slmded figures, not figures of flic
type given by G. W. MULLER in his work of 1908; unsculptured shells are drawn most
con-veniently in transmitted light and without any shading.
The cross-striation of the selvage is most often very slight; it is exaggerated in the
drawings in order to show what is selvage.
In describing the 1 i m b s we m u st note: The relative length of the joints
of an appendage has sometimes been shown below in a way that is illustrated by the following
example: I II ^: III ’!.... VIII 0.5. liere the roman figures dénoté the numbers of the
<< prev. page << föreg. sida << >> nästa sida >> next page >>
