1207 
my material of these Ostracods just as Paracypris polita O. Sars 
(4, p. 378) seems to possess. 
Especially the transparent valves have very clear muscle impres- 
sions. In a vertical row there are four near to each other, and then 
two more can be seen behind. 
The measurements of the rests which I had at my disposal, are 
smaller than those of the carapaces described by Brapy. The length 
of the largest valve of my material is 0,82, while Brapy gives for 
the length of the shells 0,98 mm. 
2. NESIDEA MOLENGRAAFFI n. sp. (Fig. 3, 4, 5, 6). 
1880. Bairdia attenuata G. S. Brapy, 5, p. 59, t, 11, f. 3. 
1901. a 5 J. G. Eeeer, 7, p. 425, t. 2, f. 9—12. 
1912. N(esidea) sp. G. W. Mürrer, 11, p. 249. 
The rests of this Ostracod are also rather rare. Only loose 
valves occur. 
Of a left valve the length is 0,85 mm., the height 0,6 mm. and 
the width 0,24 mm. while with a right valve these measurements 
are 0,92 mm., 0,55 mm. and 0, 23 mm. 
That these valves originate from a representative of the genus 
Nesidea appears at once from their characteristic shape (11, p. 241). 
It is directly shown that the hinge line of the left valve possesses 
a furrow and that the right valve is acute. 
I do not think the theory of Bosquer (1, p. 19) quite correct, in 
which it is stated that in the case of Nesideu (formerly called Bairdia) 
a furrow occurs on the free ridges of the left valve in which the 
sharp edges of the right valve lay themselves down, when the 
valves are shut. At least I only find directly behind the place, where 
the ventral edge is bent inwards, a raised ridge, which together 
with this encloses a furrow. Perhaps Bosqver got confused by the 
presence of rests of a “Lippe”. 
The space of the muscle impressions has also the qualities, which 
are given as characteristic of the representatives of the Mesidea 
genus. (8, p, 167). 
Characteristic of this new kind of the Nesidea genus is in the 
first place the sculpture which occurs on the outer surface of the 
valves. This consists in the presence of small, round, undeep pits, of 
which the diameter diminishes. towards the ridges of the valves, 
while at the same time they are here placed nearer to each other 
than in the middle. . 
78 
Proceedings Royal Acad. Amsterdam. Vol. XVIII. 
