studies on marine Ostracods 33 



Which of these two appendages is to be looked upon as the exopodite and which 

 as the endopodite? The fact that it is the exopodite that is most weakly developed in the 

 family Polycofidae and that it is this branch that shows the greatest tendency to lose its division 

 into joints in this family seems, at least to a certain extent, to make it probable that in the 

 families Cypridinidae and Sarsidlidae it is the weak, unjointed appendage that represents the 

 exopodite. We may in point of fact with a fair degree of certainty assume this to be the case ; the 

 relative position of the two appendages supports this explanation very decidedly, as the weak, 

 unjointed process is in almost all the forms both of the family Cypridinidae (cf. 6. 0. Sars, 

 1887, pi. VII, fig. 11) and of Sarsiellidae (cf. G. 0. Sars, 1887, pi. X, figs. 5, 6) placed at almost 

 exactly the corresponding place on the basale as the mandibular exopodite in these forms, 

 i. e. disto-lateraUy, laterally of the strong appendage; in most cases, perhaps, a very slight 

 displacement ventrally can be observed (with this orientation the maxilla is thought of in its 

 natural position, i. e. pointing obliquely forward and outward). Only in one out of all the forms 

 seen by me, Monopia (Cypridinodes) acuminata (described in this work), in which, moreover, this 

 appendage is rather strongly reduced, almost verruciform, is it placed distinctly medially of 

 the larger process and, in addition, it is very much displaced distally. Only very slight impor- 

 tance, however, should be attached to this exception, as the maxilla in the sub-genus Cypridinodes 

 must be regarded as very much metamorphosed. — Finally, if we start out from the fact that 

 this explanation of the two distal appendages is correct, there cannot be much doubt that 

 the lamelliform appendage, in most cases more or less rounded, that is found dorsally 

 on the coxale in a number of forms belonging to the sub-family Cypridinitiae is to be 

 explained as an epipodial appendage. In most cases this appendage has dense, fine hairs 

 and, in addition, it is sometimes furnished with a few bristle-like processes; cf. C. Cl.\US, 

 1873, pi. XI, fig. 27. Additional arguments in favour of this interpretation are perhaps, 

 first, the fact that this appendage is developed rather late during the ontogeny and, 

 secondly, that it is not very constant, being absent in a number of forms belonging to the 

 sub-family Cypridininae and in the sub-family Philomedinae and the family Sarsiellidae; in 

 the two latter groups it appears only in the form of ,,einen flachen, fein behaarten Hautsaum" 

 (G. W. MOller, 1894, p. 56). 



The maxilla in the family Rutidermatidae has about the same type as in the two Rntidermaiidae. 

 preceding families; its exopodite seems, however, to be almost entirely reduced; cf. G. W. ML'LLER, 

 1908, pi. VII, fig. 5. 



The morphological explanation of the different parts of the strange maxilla in the Asieropidae. 

 family Asteropidae, see fig. Ill: 4, certainly presents rather great difficulty, but nevertheless 

 it can be carried out with fairly great certainty. Presumably this limb has originally had 

 five or six joints, the protopodite having three and the endopodite two or three joints, thus 

 having the same fundamental type as in the preceding families. The long, powerful, forward 

 pointing part, situated distally of the endites, probably represents the distal joint of 

 the protopodte, the basale; the part at which the endites issue thus corresponds to the 

 procoxale and the coxale. It seems very probable that the two-jointed palp which is 

 situated distally on the basale and points downward is, as in the preceding families, homo- 



Zoolog. bidrag, Uppsala. Suppl.-Bd. J. 5 



