106 TAGE SKOGSBERG 



differeiitlv in very closely -related forms. — I may state here in passing' that I have found a 

 hitherto undesoribed genus*, quite withdiit any I urea; this genus is certainly closely related 

 to Macrocifpris. a Cvprid genus wliich is considered, probably quite correctly, to be a primi- 

 tive one. This facts of course supports G. Alm's view. — Other reasons too, obtained from the 

 seventh limb and the sexual organs, liave been adductMl by G. Alm against G. W. Ml'M.KU's 

 view (cf. G. A1..M, 1915, pp. 18—21). 



In G. Alm's opinion the four families belonging to Cypriformes have ,,beinahe gleich- 

 zeitig" entered on two separate lines of development; Darwinuliclae and Cypridae have 

 developed in one direction, Nesideidae and Cytheridae in the other. He thus denies ,,daB der 

 eine oder der andere Typus von dem zweiten abstammt" (p. 17). He considers that it is 

 difficult to decide the question as to whether the N e s i d e i d s or the C y p r i d s are more 

 closely related to the original forms, but he adds, curiously enough, that this is ,,bei meiner 

 AufEassung nicht von groBerer Bedeutung". 



This author sums up his view in the following words. ,,Das verschiedene Aussehen von 

 MCLLER's und meinem Stammbaum liegt also darin, daB nach ihm die Nesideidae-Cytheridae 

 ziemlich hoch oben am C y p r i d e n - Stamra ihre Abstammung hat, wahrend nach meiner 

 Auffassung diese beiden Gruppen, einerseits Cypridae mit der kleinen Familie Darwinulidae, 

 andererseits Nesideidae-Cytheridae, ziemlich bald nach der Abgrenzung von Myodocopa, sich 

 voneinander getrennt und nachher voUkommen selbstandig entwickelt haben." These forms 

 would consequently have branched ofi fairly soon after the Cytherelliformes. The genealogical 

 tree of the Ostracods has thus, according to this writer, the type shown in my fig. VIII. 

 This may, of course, appear to be rather similar to the genealogical tree drawn up by G. W. 

 Mt'LLER 1894, p. 191; the difference is, however, perhaps better shown by a comparison between 

 this diagram and that of G. W. Mt'LLER's as re-constituted by me in the present work, fig. IX. 



C. Glaus, in his work of 1876, p. 98, puts forward another view. According to him the 

 C y p r i d s have developed from the C y t h e r i d s. A. KaUFMANN took the same view 

 in liis work of 1900, p. 244, ,,wenn wir die marinen Cytheriden . . . als direkte Stamm- 

 formen der C y p r i d e n ansehen". Neither of these two authors has tried to give any 

 detailed reasons for their views. 



According to C. ClaUS (loc. cit.) the Cytherids have developed from the 

 Halocyprids „oder vielleicht besser von einer nahestehenden, bislang nicht naher 

 bekannt gewordenen ausgestorbenen Ostracodengruppe". According to this writer the 

 pedigree of the recent Ostracods is thus of the following type: (fig. X). (This 

 writer does not say anything about the position of the Polycopids, Nesideids and 

 the Cy there 11 ids.) 

 Summary of the re- It seems exceedingly difficult to decide how far t h e „p e d i- 



sulls of my -studies u r ^ i , i , i , i • i i , t j 



.h ^ . I i„ grees oi these three authors are to be considered correct. It 



on the mutual reta- '-' 



tions of my five main seen^s to me not impossible that G. Alm's view as to the class i- 



groups. ficatory positionof the four families belonging to Cypriformes 



is nearer to the truth than G. W. Muller's. O n the o t h e r li a n d it 



• This form will be described in n loliowing part of this work. 



