studies on marine Ostracods 41 



the comb as a whole or at least the greater part of it is homologous to the joint that is denoted 

 by me above as the fourth exopodite joint; the long bristle (or the two long bristles) on the 

 lateral side of the comb is, according to the same statement, part of the outer lobe of the joint 

 that is termed by me the third exopodite joint. 



After having had an opportunity of studying the fifth limb of the genus Pseudophilo- 

 medes Cr. W. MtJLLER, however, altered his opinion. Thus he writes, 1894, p. 63: ,,Ueber die 

 Morphologie des Fortsatzes habe ich an anderem Ort die Ansicht geauBert, daB er vielleicht 

 homolog dem Glied 4 sei, wobei ich mich auf die Aehnlichkeit mit der 2. Maxille der ^ von 

 Philomedes stiitzte; hier sehen wir das 4. Glied nach vorn gerichtet. Die einzelne Borste, welche 



auf dem auBeren Rand des Blattes entspringt, sollte den hinteren Borsten von Glied 



3 entsprechen. Zu einem anderen Vergleich giebt Pseudofhilomedes die Veranlassung. Der 

 Fortsatz entspricht in Richtung und Lage dem stark verlangerten Zahnfortsatz von Pseudo- 

 philomedes; der Haken an der Basis wiirde dann dem inneren (vorderen) Zahn, die Borste dem 

 Glied 4 entsprechen. Die Aehnlichkeit in der wechselseitigen Lage der einzelnen Theile ist auf- 

 fallig genug. Giebt man die Moglichkeit zu, daB sich ein Zahn in einen borstentragenden Fortsatz 

 umwandelt, so erscheint dieser Vergleich zutrefiender als der altere. Einstweilen muB wohl 

 die Frage in Ermangelung entscheidender Zwischenformen als offen betrachtet werden" 

 (cf. G. W. Mt)LLER, 1894, p. 60, fig. 6). In the statement just quoted joint no. 4 corresponds 

 to joint no. 7 in the statement of 1890; joint no. 8 in the statement of 1890 corresponds to the 

 outer lobe on joint no. 3 in the statement of 1894. The „Zahnfortsatz" corresponds to the 

 second joint on the part of this limb in the Cypridinidae that was termed the exopodite in the 

 homologization that I carried out above for this family. Joint no. 4 in the statement just quoted 

 corresponds to the joint that, according to the terminolog}' used by me above, is denoted as 

 the fourth joint of the exopodite. According to G. W. Mt'LLER's last statement the comb 

 is thus to be considered as homologous to the second joint of the part that is termed by 

 me above as the exopodite, the long bristle (or the two long bristles) on the outer side of 

 the comb is, according to the same statement, part of the joint termed by me the fourth 

 exopodite joint. 



The fact that G. W. MULler writes: „Giebt man die Moglichkeit zu, daB sich ein Zahn 

 in einen borstentragenden Fortsatz umwandelt" seems to indicate that this author has started 

 from the assumption that the primitive forms of the family Asteropidae were characterized by a 

 fifth limb of about the same type as in the genus Psetidophilomedes. This can, however, scarcely 

 have been the case. Although, as has been shown in another part of this treatise, of all the 

 recent forms so far known the sub-family Philo7nedinae is probably most closely related to 

 Asteropidae, the latter can by no means be considered as being derived directly from the former. 

 On the contrary, the sub-family Philomedinae must certainly be considered to have a type 

 that differs very much from the primitive form from which the Asteropids originate; 

 the fifth limb especially must be considered as being rather much modified in this sub-family. 

 On the other liand it does not seem impossible that Philomedinae and Asteropidae originate 

 from a common primitive form. The part of the fifth limb that was termed the first and second 

 exopodite joints in the homologization carried out by me above was presumably more power- 



Zooloc. Mdi-iia. Uppsalii Supi>I -Prt I " 



