Ilf)l 



studies on marine Ostrarods o65 



of 1893 and 1894. G. H. Fowler's studies of the larval stages of the H a 1 o c y p r i d s from 

 the Bay of Biscay (1909) are interesting, especially because of the application of Brooks's law. 



The above work by G. H. Fowi.EU is also of interest because in it the working supposition 

 was put forward that all the species of the genus Conchoecia (and other H a 1 o c y p r i d s) 

 ,, exhibit two stages with secondary sexual characters in the male". 



The oecology of the H a 1 o c y p r i d s is almost completely unknown. G. W. Mi^LLEU, Oerohgy. 



1894, put forward the assumption that these forms belong to the fauna of the bottom and that 

 it was only in more or less exceptional cases tliat they travelled up among the plankton. But 

 even in a treatise published the same year C. Claus put forward strong arguments in favour 

 of these forms being holoplanktonic organisms. G. H. FowLER, 1909, dealt with the vertical 

 wanderings of the Halo c y ]) r i d s, the ^iroportion between males and females and ,.the 

 Death-rate". 



Remarks: — Which of the classifications of the Halocypri formes described above is to itVoWf of ihe 

 be preferred, the one worked out by C. Claus in 1890 or that of G. W. MtJLLER, 1906 a? ab.n'e.menuoned 



^ _ _ _ _ rlfissificnlmns of this 



As will be seen from what follows, I have in the present work followed the latter entirely. >;,oi,p is to he 

 When I began my investigations of this group I considered — like G. W. MOllbr, 1906 a — preferred? 



that it was not impossible that a careful investigation of all the organs would make possible 

 and even necessitate a splitting-up of the genus Conchoecia — sensu G. W. Mt'LLERl — into 

 a larger or smaller number of genera. But the results of my investigations c^uite refuted this 

 supposition. The organs to which G. W. Muller had paid no attention in his work of 1906 a, 

 i. e. the mandible, the maxilla, the fifth, sixth and seventh limbs, the penis, the furca, the lips 

 and the internal organs are subject to exceedingly slight variation within this genus. A division 

 of Conchoecia into a number of genera, i. e. into units placed parallel systematically to Archiconch- 

 oecia, Halocypris and Euconchoecia, thus seems impossible to me too. On the other hand 

 we can — as G. W. MOller pointed out — distinguish more or less distinct and presumably 

 natural groups within the first-mentioned genus. A number of these groups are rather strikingly 

 characterized, e. g. the Rotundata group by the position of the unsymmetrical glands, the Curta 

 group by the ramosity of one or more of the bristles on the first antenna. These groups, wliich 

 are easily defined and characterized, can, of course, be distinguished as special sub-genera. But 

 the method employed by G. W. MUller seems to me preferable on account of its uniformity 

 and consistency. A number, or, more correctly, most of the groups established by G. W. MOller 

 are very difficult to define; they are so interwoven in each other — often presumably by con- 

 vergence — that the natural position of a good many of their species is and will |)n'suiiial)lv 

 always be exceedinglv problematical. 



As has been pointed out above on tliis page G. H. FOWLEH, in his work on the planktonic (-'.//. Fowler's 

 s t r a c o d s of the Bay of Biscay (1909). put forward the interesting and, if correct, exceed- '"PP"''''"" "f '"' 



. ." . . . . mature stages in tin 



ingly important working supposition that all th(> species of the genus Conchoecia ,, exhibit Hahiypnds. 

 two stages with secondary sexual characters in the male" (p. 'Irtd,). i. e. these species have to 

 undergo a further moult after they have attained maturity. According to this author a number 

 of characters are altered (lurin<r the last moult. On account nf this two forms were in several 



