u 



TACK SKOGSIiERG 



StatemeiUa 

 III jrequency. 



I'Uiiikton samples. 



Stat<:inenls of 



locality. 



H ftoricat resumes. 



Final irmaili. 



joints, the figures above the line denote the relative length of the joints on the dorsal or anterior 

 .side, the figures below the line the relative length of the joints on the ventral or posterior side. 



I may point out in passing that when I speak below of bristles that are more or less 

 finely pectinated distally, this pectination is presumably always in two rows, even if it is 

 shown in one row in the drawing; the two rows of spines are often situated on the same side, 

 so that what is apparently one row of pectination seems to be present. This pectination could, 

 of course, only be reproduced in outline. 



It is often rather difficidt to estimate the number of bristles because they are situated 

 .so close together. G. W. MOller complains about this, 1894, p. 28 ... . „Wer die Schwierig- 

 keit einer genauen Feststellung dieser Verhaltnisse kennt . . . ." I think I have overcome 

 this difficulty, at least partly, by a simple manipuhition : the limb (in glycerine) is crushed 

 by a shght pressure on the cover-glass and then the latter is moved, if desired, in different 

 directions. By this procedure bristles that are placed close to each other are sejjarated. I have 

 obtained very good results with this method. Chitinous parts ought not to be reproduced from 

 fresh material; the material ought first to be hardened in alcohol, or else the chitinous parts 

 are too strongly compressed by the cover- glass and misleading images arise. 



In the descriptions given in this work the penis is described rather superficially, 

 but I hope that the drawings that are given of this organ will, in spite of their being done in 

 (luthne, prove to be sufficiently detailed to permit of quite certain identification of species. 

 I hope to have an opportunity in a subsequent work to give more detailed descriptions and 

 reproductions of this organ which is so interesting from a morphological point of view. 



Although it is almost always stated below how many specimens of each species were 

 L-aught, this information cannot be used, except with very great caution, as an indication of 

 the frequency of the forms in question, as the samples that were investigated were not collected 

 for comparative quantitive investigations. 



All the plankton samples were caught in open nets. The statements as to depth given 

 under these forms are consequently of comparatively little value. 



All statements as to tlie longitude of the localities are made with reference to Greenwich. 



A historical resume is given after each of the higher systematic units, sub-families, 

 famiUes, etc. These resumes deal chiefly with the historical development of our knowledge 

 of the classification of the Ostracod group and the organs that are most important for the 

 special classification, the shell, appendages, external sensory organs, etc. 



Before ending this introduction and giving the results of my investigations I wish to 

 quote a statement made by Til. Mohtensen in liis distinguished work on the Echinoids of the 

 Ingolf Expedition, 19(i3, p. 3: „D e t v i s t e s i g, a. t D y r e n e v a r s a e r d e 1 e s g o d e 



m (> g t> t V e 1 k a r a k t e r i s e r e d e. D e t e r 

 s k e 1 i g li (' d (' r n e g c ii n e m den U e n d e- 

 1 i g h (■ (1 a f (I a a r 1 i g e B e s k r i v e 1 s e r, d e n r u m m e r."* This remark coincides 

 entii-ely with the experience I obtained myself in carrying out the ]iresent work. 



at have med at gore, Art erne 

 L i t e r a t u r e n, d e r b r i n "■ e r V a 



• Traiisl<ili>,n: Tlir .iiiiiii.ils |inivr,l h, !„■ very -ou.l lo work willi. Ihc s|n'c irs wrrr viTV \\•^^\\ (lisliu-iiislii'd. 11, is 

 llii; liliT:iliiiv lliiit citiiws .lilTicully on j.c.nnil iil' \Ur ixvv:,\ iiiiiilliiT ol' |MHir ilr^icripliciiis il coiiliuns. 



