studios on rnnrinr Ostrarods 



11 



Uijjereiuv beliieeii 



external and 

 internal chnraclcrs. 



I have unfortunately had no opportunity of contributing to any great extent to this 

 work of clearing the path of study. The conditions brought about by the war were a decisive 

 obstacle to this. I have only succeeded in getting type specimens of a few previously described 

 species; see the preface. 



The main object of this work of mine became consequently to make as large a number 

 of species well known as possible. . . Although now that the first part of this work is nearing 

 its close I feel that I have not attained the precision and comprehensiveness at which I ventured 

 at one time to aim, yet I put forward the results that I have obtained in the hope that the 

 descriptions given below may prove to be satisfactory both for certainty in the identification 

 of species and for establishing the positions of the forms in question in the natural system. 



L. Plate, in his above quoted essay „Prinzipien der System a tik, etc.," 

 1914, writes, p. 148: „Ganz allgemein laBt sich behaupten, daB die auBerlich sichtbaren Organe 

 der Tiere schon aus dem Grunde zur Diagnose besonders geeignet sind, well sie viel verander- 

 licher sind als die inneren. Nah verwandte Arten sind haufig nur an solchen Differenzen der 

 Hautskulptur, der Fiirbung, der Hautanhange, der Schalen, der Siunesorgane zu imterscheiden, 

 wahrend sie in den inneren Organen gleich oder fast gleich gebaut sind. . . . Selbst Arten aus 

 verschiedenen Gattimgen sind gar nicht selten an inneren Organen nicht zu erkemien." 

 I have made the same observation with regard to the marine Ostracods. The external 

 characters are much more variable than the internal ones, a state of affairs that, as L. PLATE 

 writes (loc. cit.), is presumably due to the fact that the former „von dem bestandigen Wechsel 

 der auBeren Faktoren in erster Linie getroffen werden". As a rule only the higher systematic 

 units differ from each other in the internal characters, such as the digestive organs, the inner 

 sexual organs, etc. One consequence of this is that in the descriptions of species and genera 

 I have given below I have dealt almost exclusively with outer characters taken from the shell, 

 limbs, furca, the outer sexual organs and sensory organs. — The inner characters, the nervous 

 and the digestive systems, the inner sexual organs and musculature, which have been partly 

 worked out in a very meritorious way by preceding authors, for instance G. W. MOller, 1894, 

 I hope to have an opportunity to deal with in more detail in a subsequent work in connection 

 with a comparative morphological study of these forms. 



A consequence of the incompleteness and uncertainty of the great majority of the My descriptions ui 

 preceding descriptions of species is of course that it is at present often quite impossible to decide /«""''«* "'"^ genera. 

 the value of a character from a systematic point of view, i. e. it is impossible at present to 

 establish detailed family and genus diagnoses of a definitive nature. It is therefore necessary, 

 when more detailed diagnoses are now worked out, to burden the descriptions of species in many 

 cases with a multitude of characters of a higher systematic value, characters which may 

 gradually be transferred to genus or perhaps even to family diagnoses according as the number 

 of the well described species increases. In the cases where I had a comparatively abimdant 

 material of the same family or genus at my disposal I worked out comparatively detailed family 

 and genus descriptions in order to avoid too much repetition. In these descriptions, which are 

 to be taken as quite provisional, I have collected all or at any rate most of the characters that 

 I found common to all the species of the family or genus in question that were investigated 



