Bemerkninger. — Nerverende Phyllopode er 
allerede i Aaret 1785 beskrevet af O. Fr. Miiller 
som Lynceus brachyurus. At den senere som Hedessa 
Sieboldi af Liévin opforte Form er identisk med 
Miiller’s Art, er forst sikkert bleven constateret af 
Grube. Af de fra andre Verdensdele opforte Arter 
synes de 2 nordamerikanske, L. Gouldii Baird og L. 
mucronata Packard at komme vor Art meget ner. 
Derimod afviger de 2 australiske Arter, L. macleayana 
King og ZL. Tatei Brady, som jeg begge har havt 
Anledning til at undersoge noiere, meget bestemt i 
Henseende til Formen af Rostrum. Af den euro- 
pewiske Art har Grube givet en meget udforlig og 
indgaaende Beskrivelse, ligesom han ogsaa forst har 
givet nermere Oplysninger om dens eiendommelige 
Larveudvikling. 
Beskrivelse af Hunnen. 
Skallen har hos de storste af mig indsamlede 
Exemplarer en Lengde af 41/2 mm. og en Heide af 
3,80 mm. Den bestaar, som hos Limmnadia, af 2 
tydeligt begrendsede Valvler, forbundne med _hin- 
anden langs Dorsalsiden. Forbindelsen er temmelig 
ulig den hos Limnadia og gjor mere Indtryk af at 
vere en virkelig Laas, i Lighed med hvad man 
finder hos Ostracoderne. Medens nemlig hos den 
‘sidstneevnte Slegt de 2 Valvler stoder sammen oven- 
til under en spids Vinkel, danner de her, for de for- 
binder sig med hinanden, en pludselig Omboining 
eller Fold, hvorved Forbindelsen mellem begge kom- 
mer til at ligge i Bunden af en dyb Fure, der 
strekker sig langs Rygsiden af Skallen (se Tab. 
XVII, Fig. 7 og 8). Seet fra Siden (Fig. 6), har 
Skallen en noget uregelmessig rundagtig Form, med 
den storste Hoide, der falder over den forreste Del, 
nesten ligesaa stor som Leengden. Dorsalkanten er 
kun meget svagt buet og skraat heldende bagtil, 
forbindende sig med den bagre Kant uden nogen 
tydelig Vinkel. Fortil er der en noget fremsprin- 
gende, men afrundet Forhoining, hvor Dorsalkanten 
forbinder sig med Forkanten. De frie Kanter af 
Valvlerne danner en fuldkommen jevn og uafbrudt 
Bue, som dog er noget fladere fortil, hvorfor ogsaa 
Skallen viser sig fortil ligesom stumpt afkuttet, 
medens den bagtil er mere jevnt afrundet. Seet 
ovenfra (Fig. 8), viser Skallen sig overordentlig steerkt 
buget, bredt «gformig, med den storste Brede bag 
Midten, og noget mere afsmalnende fortil end bag- 
til, hvor den pludselig indsnevres til en kort stump 
Fremragning. Naar, som sedvanlig er Tilfeeldet, 
Valvlerne er halvt aabne (se Fig. 2), synes Skallen, 
ovenfra eller nedenfra seet, end bredere og nesten 
fuldstendig kugleformig. Dreies Skallen saaledes, 
118 
at the point. Colour, a dark olive-green. 
of the shell, up to 4’/2 mm. 
Remarks. — This Phyllopod was described by 
O. Fr. Miller as early as the year 1785, under the 
name of Lynceus brachyurus. That the form subse- 
quently described by Liévin as Hedessa Sieboldi is 
identical with Miiller’s species, was first proved 
with certainty by Grube. Of the species described 
from other quarters of the globe, the 2 North Ame- 
rican species, L. Gouldii, Baird, and L. mucronata, 
Packard, seem very much to resemble our species. 
On the other hand, the two Australian species, L. 
macleayana, King, and ZL. Tatei, Brady, both of 
which I have had the opportunity of examining 
minutely, differ very decidedly in regard to the 
form of the rostrum. Grube has given a very 
detailed description of the European species, and 
was also the first to give any exact information 
about its peculiar larval development. 
Length 
Description of the Female. 
In the largest of the specimens collected by 
me the shell has a length of 41/2 mm. and a height 
of 3.80 mm. It consists, as in Limnadia, of 2 dis- 
tinctly defined valves, connected with one another 
along the dorsal side. The connection is rather 
unlike that in Limnadia, and gives more the impres- 
sion of an actual hinge, such as is found in the 
Ostracods; for while in the latter genus the 2 valves 
meet above in an acute angle, they here, before 
joining one another, form a sudden bend or fold, ~ 
thereby causing the connection between them to lie 
at the bottom of a deep furrow, which extends along 
the dorsal side of the shell (see Pl. XVIII, figs. 7 
and 8). Seen from the side (fig. 6), the shell has a 
somewhat irregular, rounded form, with the greatest 
height, which falls over the foremost part, almost 
equal to the length. The dorsal margin is only 
very slightly curved, and inclines obliquely back- 
wards, uniting with the hind margin without any 
distinct angle. In front there is a very projecting 
but rounded prominence, where the dorsal margin 
unites with the anterior. The free edges of the 
valves form a perfectly even and uninterrupted 
curve, which, however, is rather flatter in front, 
thus causing the shell to appear anteriorly as if 
bluntly truncated, while at the back it is more 
evenly rounded. When seen from above (fig. 8), the 
shell appears to bulge very much, and is broadly 
ovate, with the greatest breadth behind the middle, 
and rather more tapering in front than behind, 
where it suddenly contracts into a short, blunt pro- 
jection. When, as is usually the case, the valves 
are half open (see fig. 2), the shell, when seen from 
above or below, appears still broader and almost 
spherical. When the shell is turned in such a way 
