studies on marine Ostracods 55 



as more or less primitive in a number of respects, as, for instance, in P o 1 y c o p i d s, H a 1 o- 

 cyprids, Macrocyprids and Cytherellids. 



Finally the fact that the vibratory plates on the mandible and maxilla are presumably 

 of an epipodial nature may also be advanced to support this explanation. With regard to the 

 value of this argument see p. 52 above. 



If we start from the assumption that the vibratory plates on the fifth, sixth and seventh 

 limbs are homologous with epipodial appendages, how is that part of these limbs to be 

 explained that is situated distally of the protopodite and is often pointed backward and 

 rod-shaped? Is it to be looked upon as an exopodite or an endopodite? And liow is the 

 forward pointing process on the fifth limb to be explained? 



The position of these organs in relation to the limb as a whole does not — I think 

 — permit of more than one explanation, the one which has already been put forward by me 

 and called the first method of explanation. According to this the forward pointing process on 

 the fifth limb is to be homologized with the endopodite; the part that is in most cases rod-shaped 

 and pointing backward corresponds to an exopodite that is turned somewhat backward. 



This is opposed to the results of all previous investigators; in all previous works, as is 

 seen above, the distal part of these limbs has been explained as the endopodite. In the case 

 of those investigators who homologize the vibratory plates on all limbs with exopodites this 

 result is quite natural. But it seems to me exceedingly curious that G. W. MULLEH, who has 

 interpreted the vibratory plates on the three posterior limbs as epipodial appendages, should 

 have been able to arrive at this result. 



What arguments can G. W. MOller bring forward in favour of a homologization of the 

 two branches of the fifth limb that is quite the opposite of what is assumed by me above? 



It is quite clear that the position of these organs does not support this view. G. W. 

 MULLER writes with regard to this, 1894, p. 196: ,,Nicht unerwahnt will ich lassen, daC die Art 

 der Einlenkung die umgekehrte Deutung befiirwortet, doch wird man auf diese Thatsache 

 wenig Werth legen, mit Riicksicht darauf, daB es nur einer geringen Verschiebung, einer 

 schwachen Verbreiterung des Stammes an der betreiienden Stelle bedarf, um die heutige Form 

 herzusteUen." In other words this author admits that the position shows his explanation to 

 be quite incorrect. At the same time, however, he tries to diminish the value of the evidence 

 of the position by stating that a slight displacement of the parts in question would be enough 

 to produce a position that would be suitable for the homologization accepted by him. When 

 the foliaceous fifth limb of the P h y 1 1 o p o d s is in a position of rest, the endites and the 

 endopodite are pointing obliquely inwards and forwards towards the mouth; the exopodite 

 is pointing obliquely backwards and outwards. On the foliaceous fifth limb in the family 

 Cypridinidae, when the organ is in a position of rest, the endites point forwards and inwards, 

 the part that G. W. MUlleh explained as an endopodite points obliquely backwards and out- 

 wards. On the same limb in the C y p r i d s and Cytherellids the process that was 

 explained by G. W. MtJLLER as an exopodite is, when the limb is in a position of rest, pointing 

 inwards and forwards; the rod-shaped branch which was explained by the same author as an 

 endopodite, points backwards. The homologization carried out by G. W. MCller thus makes 



