118 



Bemærkninger. — Nærværende Pliyllopode er 

 allerede i Aaret 1785 beskrevet af 0. Fr. Muller 

 som Lyncms hraciiyurus. At den senere som Hcdcssa 

 Sicholdi af Liévin opforte Form er identisk med 

 Miiller's Art, er først sikkert bleven constateret af 

 Grube. Af de fra andre Verdensdele opforte Ai'ter 

 synes de 2 nordamerikanske, L. Goiddii Baird og L. 

 mucronaia Packard at komme vor Art meget nær. 

 Derimod afviger de 2 anstraliske Arter, L. macleayana 

 King og L. Tatei Brady, som jeg begge liar havt 

 Anledning til at undersoge noiere, meget bestemt i 

 Henseende til Formen af Rostrum. Af den euro- 

 pæiske Art bar Grube givet en meget udforlig og 

 indgaaende Beskrivelse, ligesom han ogsaa forst bar 

 givet nærmere Oplysninger om dens eiendommelige 

 Larveudvikling. 



Beskrivelse af Hunnen. 



Skallen bar hos de største af mig indsamlede 

 Exemplarer en Længde af 4 Va mm. og en Hoide af 

 3,80 mm. Den bestaar, som hos Limnadia, af 2 

 tydeligt l^egrændsede Valvler, forbnndne med hin- 

 anden langs Dorsalsiden. Forbindelsen er temmelig 

 ulig den hos Limnadia og gjor mere Indtryk af at 

 være en virkelig Laas, i Lighed med hvad man 

 finder hos Ostracoderne. Medens nemlig hos den 

 sidstnævnte Slægt de 2 Valvler stoder sammen oveji- 

 til under en spids Vinkel, danner de ber, for de f(jr- 

 binder sig med binanden, en jiludselig Omboining 

 eiler Fold, livorved Forbindelsen mellem begge kom- 

 mer til at ligge i Bunden af en dyb Fure, der 

 strækker sig langs Rygsiden af Skallen (se Tab. 

 XVIII, Fig. 7 og 8). Seet fra Siden (Fig. 6), har 

 Skallen en noget uregelmæssig rundagtig Form, med 

 den storste Hoide, der falder over den forreste Bel, 

 næsten ligesaa stor som Længden. Dorsalkanten er 

 kun meget svagt buet og skraat heldende bagtil, 

 forbindende .'^ig med den bagre Kant uden nogen 

 tydelig Vinkel. Fortil er der en noget frem-sprih- 

 gende, men afrundet Forhøining, hvor Dorsalkanten 

 forlnnder sig med Forkanten. De frie Kanter af 

 Valvlerne danner en fuldkommen jevn og nafbrudt 

 Bue, som dog er noget fladere fortil, hvorfor ogsaa 

 Skallen viser sig fortil ligesom stumpt afkuttet, 

 medens den bagtU er mere jevnt afrundet. Seet 

 ovenfra (Fig. 8), viser Skallen sig overordentlig stærkt 

 buget, bredt ægformig, med den største Brede bag 

 Midten, og noget mere afsmalnende fortil end bag- 

 til, hvor den pludselig indsnævres til en kort stump 

 Fremragning. Naar, som sædvanlig er Tilfældet, 

 Valvlerne er halvt aabne (se Fig. 2), .synes Skallen, 

 ovenfra eller nedenfra seet, end bredere og næsten 

 fuldstændig kugleformig. Dreies Skallen saaledes. 



at the point. Colour, a dark olive-green. Length 

 of the sliell, u]) to A^/i mm. 



Remarks. — This Phyllopod was descrilied l)y 

 0. Fr. Mtiller as early as tlie year 1785, under the 

 name of Li/ncens brach/urus. Tliat tlie form subse- 

 quently described by Liévin as Hedcssa Sieholdi is 

 identical with Miiller's species, was first proved 

 with certainty by Grube. Of the species described 

 from other ([uarters of the globe, the 2 North Ame- 

 rican species, L. Goiddii, Baird, and L. mucronata, 

 Packard, seem very much to resemble our species. 

 On the other hand, the two Australian species, L 

 macleayana, King, and L. Tatei, Bradj-, both of 

 whicli I have had the o])portunity of examining 

 minutely, difier 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. 



Description of the Female. 



In the largest of the specimens collected by 

 me the shell lias a length of 4V2 mm. and a height 

 of 3.80 mm. It comsists, 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 alcove in an acute angle, the\' here, before 

 joining one another, form a sudden bend or fold, 

 thereby causing tlie 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 tlie 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 an^- 

 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 fiatter in front, 

 thus causing the shell to appear anteriorly as if 

 bluntly truncated, while at the back it is more 

 evenly roiinded. "When seen from above (fig. 8), the 

 shell apjiears 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 ])ro- 

 jection. When, as is usually the case, the valves 

 are half open (see fig. 2), the shell, when seen from 

 above or below, a])pears still broader and almost 

 spherical. When the sliell is turned in such a way 



