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TAOE SKOOSBRRO 



111 t he ])nst('ri(ir p;irt ol t.lic 

 duct, opening (Hit ventrally 



Itod-shnprd orgnn. 



Summary of my 

 rrilicism of G. II'. 

 Mailer's opinion of 



ihp Prrifostrnrod-<. 



'The fundamental 



tlif 1' r o t t> s 1 r a () il s corsisti'd nl two .siiii|)l(' s;u-l<.>< sifiiatci 

 IhkIv; from cacli of tln'.'^c sacks tlicii' was a simply constructoi 

 just in fvoiit of till' furra: on tlif otlicr haiul it soonis to n\v to he quite uncertain 

 whothor the sexual ducts opened outwards with a simple or a paired orifice. In the males 

 the posterior pair of legs was userl in copulation and was developed into the two penes. 

 The fate of this pair of legs in the females is imcertain; there is possibly a remains 

 of them in the genital verrucae. Among the recent Ostracods the most primitive con- 

 ditions seem to be found in ;i nuinlicr of Cy p r i d i n i d s, possibly, for instance, in Philo- 

 medes and Asterope. 



Did the Protostracods have a rod-shaped organ? 



G. W. Mt'LLRR does not make any statement on this point either. ('. Clams expresses 

 himself (1876, p. 97) in such a way that one can scarcely doubt that he considered that they 

 had. I scarcely think, however, that they had. Among the recent s t r a- 

 c o d s this organ is absent not only in C y p r i d s, D a r w i n u 1 i d s, N e s i d e i d s, 

 C v t h e r i d s, but also in C y t h e r e 1 1 i d s and P o 1 y c o p i d s, which we are accustomed 

 to consider as being in many respects rather primitive and in the genus that is in several 

 respects presumably the most primitive among the H a 1 o c y p r i d s, namely Thaumatocypris. 

 (Jnly in the Cypridinids and most of the H a 1 o c y p r i d s is it developed. I myself 

 have only had an opportunity of investigating one species of Polycopidae. This was charac- 

 terized by two bristles, situated rather near each other on the front of the head, on 

 each side of the place where the rod- shaped organ is situated in the Cy p r i d i n i d s. Do 

 these bristle^s correspond to the similarly situated bristles in other lower Crustacean groups? 

 Is this a primitive stage? It seems to me by no means impossible that this is the case. It seems 

 difficult to assume that a rod-shaped organ existed originally and was then completely reduced 

 in all these forms. The fact that this organ is absent in the most primitive genus of the 

 H a 1 o c y p r i d s even seems to indicate that the appearance of this organ in Cypridinids 

 and Halo c v p r i d s is not, as C. Claus has assumed, the result of common inheritance, but 

 that we have here once more a phenomenon due to convergence. 



This investigation has thus shown that while it is true that we can say with some 

 degree of certainty in the case of a number of characters that they are original, our whole 

 knowledge of the organization of the Protostracods is very incomplete and uncertain, a 

 good deal more uncertain than one would imagine from G. W. MUller's exposition. 



G. W. MuLLER gives the results of his investigation of the mutual relationships of 



191. 



classification of the ^^^ ^^^^^^ s t r a c o d s in his monograph of 1894, pp. 188- 



recent Ostracods ar- . t ■ j j • 



cording to c. If. The most important of these rcsults is that the recent Ostra CO ds are to be divided mto 



Mailer. j^^YO main natural groups, sharply divided from each other, Myodocopa and Podocopa. To the 



former belong Cypridinids, Halocyprids and P o 1 y c o p i d s, to the latter 

 Cyprids,- Darwinulids, Nesideids, Cytherids and Cytherellids. 



The view that these animals can be divided into two natural, sharply differentiated 

 — „scharf getrennte" — main divisions is, as is shown above, decidedly opposed to the views 

 of C. 0. S-\RS and C. Ci.AU.?. As a matter of fact (i. W. MCller is almost alone in this view. 



