studies on marine Ostracods 1'.) 



limbs the fifth, sixtli and seventh limbs or the third, fourth and fifth post-oral limbs; sometimes, 

 however, he uses the terminology employed in the special part in this part as well. 



Referring to the above quoted statement of W. GlESBRECHT, G. W. MCllbh points 

 (nit, liowever, even in this work the desirability of employing a consistent terminology for these 

 organs, based on their homology. Then he writes, p. 195: ,,.... IJie Bezeichnung, ohne 

 Riicksicht auf die Function, einfach von der bei anderen Krebsordnungen zu entnehmen, 

 scheint mir schon wegen der Unsicherheit der Homologie unzulassig. So ware es wohl fiir 

 spatere Arbeiten das Gerathenste, die betreffenden GliedmaaBen einfach als 3., 4., 5. postorale 

 oder schlechtweg als 5., 6., 7. zu bezeichnen wobei wir freilich wieder bedenken miissen, daS 

 sie den 5., 6., 7. anderer Ki-ebse nicht homolog sind." 



In his later works, in accordance with this statement, G. W. .MCLleh applies the same 

 terminology for all appendages in all Ostracod groups. In these works the three posterior 

 pairs of limbs are not, however, given names in accordance with any of his two suggestions 

 quoted above, but are called instead: the first, second and third thoracal limbs. — Other 

 authors, such as, for instance, G. Alm, 1915, have adopted this terminology. 



On the other hand W. GlRSBRECHT, who also uses a terminology that is applied consist- 

 ently to all Ostracod groups, calls these three limbs in his work of 1913: the second 

 maxilla, the first and second thoracopods. 



Which of these suggestions is the most convenient to adopt? 



Even in his above quoted statement of 1894 G. W. MUllkh indicates, as is seen, tliat 

 there is difficulty in carrying out a certain homologization between the appendages of the 

 Ostracods and those of other Crustacean groups. The difficulty there indicated is the 

 uncertainty with regard to the interpretation of the fifth limb of the Ostracod s. While 

 some investigators (for instance, G. 0. Sahs and W. GlEsBRECHT) are of the opinion that the 

 fifth limb of the Ostracods is homologous with the second maxilla of other Crustacea, 

 other writers (G. \\. MUeleu among them) definitely state that this limb in the Ostracods is 

 to be taken as homoh)gous to the first thoracal limb in the higher CruHacea, the second ma.xilla 

 being quite absent in the Ostracod s. To support this opinion of his G. W. MCeeeh in his 

 work of 1894, p. 179 brought forward a noteworthy argument from the embryology of the 

 C y p r i d s. He points out that while a new limb appears at each of the first, third, fourth 

 and fifth larval moults, no new appendage is formed at the second larval moult, the moult 

 at which the second maxilla ought to appear. He illustrates this state of affairs by the follow- 



