studies on marint Ostracods I'H 



It is true that the f u r c a in Myodocopa is of a relatively uniform type, but, as is shown Furcn. 



on p. 95 above, it is by no means impossible that we are dealing here with a phenomenon ol' 

 convergence. In Podocopa this organ is subject to very considerable variations. 



The sexual organs vary very considerably in both Myodocopa and Podocopa Scj,uai org(w<. 

 and it is certain that they cannot be adduced as evidence either for or against the classifica- 

 tion made by G. W. MOller. These organs seem to be rather primitive in Myodocopa. 



Nor can the alimentary organs be used in support of G. W. Muller's view. The type .iinnrKUini i,r-^>ins. 

 found in Myodocopa seems in all probability to be comparatively primitive. These organs are 

 not known in the Cytherella. 



A heart is found in C y p r i d i n i d s and H a I o c y p r i d s, but is absent in Heart. 



P o 1 y c o p i d s and Podocopa. It existed in the P r o t o s t r a c o d s. 



Lateral eyes are only found in C y p r i d i n i d s. They were certainly to be %'-■• 



found in the Protostracods. A median eye is found in C y p r i d i n i d s and 

 most Podocopa. It existed in the Protostracods. 



The rod-shaped organ is found in C y p r i d i n i d s and H a 1 o- /in/i-^imfmi „r^nii. 

 c y p r i d s, but is absent in the others. In the two former groups we are presumably con- 

 cerned with a phenomenon of convergence: see p. 96 above. 



Are there any other organs that might be used to support this classification of G. W . '>(ii<-r "iiicn-^. 

 MiJLLER's? This question must, I think, be answered in the negative. 



It will be seen fi'om this that G. W. Muller's statement that the recent s t r a- Smumdnj uj my cm- 

 cods can be divided into two sharplv differentiated natural main groups can scarcelv "''^''' , "' . ': ; 



^ ■ . . '' Mailer s opinion lliiii 



be considered as justified. The characters on which he based his assumption are partly ,/,e recent Ostracods 

 such as he himself considered primitive and partly such as we have reason to believe have '"''^ '" '"" dt^'ided mio 



two ninin ^rnups. 



arisen by convergence. 



In my opinion the C y p r i tl i n i d s. Halo c y p r i d s. I' o I y c o p i d s ritr main groups of 



d/1 , 1 1 1 • J i i' 1 1 I • X' i' .^ ■ i. 1 'PI ''"' rereiit Oslraro/ls 



L y t h e r e 1 1 1 d s form four well d i t i e r e n t i a t o d <f i- o u n s. I li c 



•' '^ ' iircoratng to my 



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 and G v t li c t- i d s a i' e. on t h e o t li e r nnimon. 



hand, comparatively closely related to i' a c h o t h e r; t h e y might 

 conveniently be included in a h i g li e r c I a s s i f i c a t o r y u nit, b y 

 the side of the four groups m e n t i o n e d a 1) o v c Thus, in my opinion, the . 

 Ostracods ought to be divided into five main groups*. 



This view coincides on the whole with that of G. (). S\l:s; it really differs from this 

 author's view only by the division of the Myodocopa into two groups, equivalent to the three 

 other groups, the G y p r i d i n i d s and H a I o c y p r i d s having been separated. It agrees 

 with G. Glaus's view inasmuch as the Halo c y p r i d s are not grouped with the G y p r i- 

 d i n i d s in a higher classificatory unit but differs from it l)ecause these two grouj)s are taken 

 as sub-orders and because each of them is considered t(j be parallel to the group composed ot 

 the imited families Cypridae. Darwinulidae, Nesideidae and Cytheridae. 



The question as to whether these five groups are to be considered as being of quite the 

 same classificatory value cannot be answered at present with certainty. 



* With i-csjai-il lo the . Iiaiac ti-ri/Klidn ul thcsi- i;niups 1 iiced uiily ix-rer htTi- to lla- group diu^'iiusos givi'U lirlow. 



