2tl TAdK SKOdSHHHi; 



A hracket rovuul u tiguro donotes that the liml) witli this iiunilicr is mily Imind in thi 

 form of ,,stuMiinolf6rniige, imgoglioderte oder undovitlich gegliederto, iiici.st auch unbewegliche 

 Anlage"", a tiguiv without a hrackot denotes that the limb in question is more or less fully deve- 

 loped. * ilenotes the undeveloped secoiul maxilla. The same state of affairs is also found 

 in the family Ci/theridae ,,die Liicke zwischen 4. and 5. GliedmaaBe tritt noch deutlicher hervor" 

 (1894, p. 182). 1 must leave the question open as to the value of this argument. It ought to 

 be noted, however, that in the Cypridiiiids the development of the limbs is quite 

 independent of the moults, a fact that I myself have had an opportunity of observing during 

 very eareful investigations of the embryology of these forms. Another argument for G. W. 

 Mil. lkr's view is perhaps to be found in the fact that in the C 1 a d o c e r s, which are 

 presumably rather closely related to the Ostracods, this appendage is very much reduced: 

 it is observable in young specimens, but it persists only very seldom in mature individuals 

 (e. g. in Sida and Moina). On the other hand what we know so far about the nervous system 

 of the Ostracods does not seem to support G. W. MUller's opinion; it is to be noted, 

 however, that our knowledge of this subject can by no means be said to be too certain. In 

 my opinion, the problem of the nature of the fifth appendage in the Ostracods must still 

 be considered as being unsolved. A very thorough embryologico -histological investigation 

 is needed for the solution of this question. 



On account of this I am of the opinion that it is not convenient at the present time to 

 carry out a consistent terminology for the Ostracods in accordance with the principle 

 laid down by W. GlESBRECHT. 



There is in addition another reason, which seems to me rather strong, for rejecting the 

 terminologies employed both by W. GlESBRECHT and by G. W. MOller in his later works. 

 In the Crustacea we understand by the thorax, according to modern terminology, if this term is 

 taken as a strict morphological conception, the eight post-cephal segments in Leptostra,ca 

 and Malacostraca as opposed to the cephalon and pleon of these forms. It seems as if this 

 term ought not at aU to be used in the case of Entomostraca. W. GlESBRECHT writes on this 

 point as follows, 1913, p. 20: ,,Da also der vordere Rumpfabschnitt der Entomostraca deui 

 stets aus 8 Metameren bestehenden Thorax der Leptostraca und Malacostraca nicht homolog 

 ist, und auBerdem sein morphologischer Inhalt (Metamerenzahl) audi iunerhalb der Entom- 

 ostraca variiert, darf man ihn nicht ebenfalls Thorax nennen, sondern wir bezeichnen ihn als 

 Vorderrumpf und den hinteren Abschnitt als Hinterrumpf." If thus that part of the Ostracod 

 body on which the three posterior appendages are attached ought not to be called the thorax, 

 these appendages cannot, of course, be conveniently called thoracal either. 



The homologization of the limbs in the different Ostracod groups that is now generally 

 adopted seems, on the other hand, to be fairly well founded. 



Starting out from these facts I have in the present work, like most of the preceding 

 writers, termed the first four limbs of the Ostracods the first and second antennae, 

 the mandible and the maxilla; in other words in the case of these organs I have employed the 

 same terminology as that which is now used in other Crustacea. For the three posterior 

 appendages I have tried to find terms that were neutral and at the same time followed 



