254 
CRUSTACEA, 
with an oval shell resembling that of a molluscous bivalve, and tlie 
ovaries are always internal. Such is the 
Limnadia, Ad. Brong. * 
The Limnadise ai’e so closely allied to the preceding subgenus, that 
the only species known was placed among the Daphniae by the 
younger Hermann. The shell is bivalve, oval, and incloses the body, 
which is elongated, linear, and inflected forwards. In the head, and 
almost confounded with it, Ave find : 1, two eyes closely apin’oxi- 
mated and placed transversely ; 2, four antenna?, tAVO of Avhich are 
much the largest, each composed of a peduncle of eight joints and 
of two setaceous branches or threads divided into eight segments and 
someAvhat silky ; the tAVO others are intermediate, small, simple, and 
widened at base; 3, the mouth, situated beneath, and consisting of 
tAA"o inflated mandibles arcuated and truncated at the inferior extre- 
mity, and of tAvo foliaceous jaAvs. These parts, Avhen united, form a 
sort of inferior rostrum. The body, properly so called, is divided into 
tAventy-three segments, each of Avhich, except the last, bears a pair of 
branchial feet. All these feet are similar, strongly com])rcssed, and 
bifid;, their externa) division is simple, and ciliated on the exterior 
edge; the other 1ms four joints, and is strongly ciliated along its inte- 
rior margin. The first tAvelvc pairs are of equal length, and larger 
than the others; the length of the latter progressively diminishes. 
The eleventh pair, and the tAVO folloAving ones, have a slender 
thread at their base, AAdiich ascends into the cavity situated betAveen 
the back and the shell, in order to support the ova. The last seg- 
ment on the tail is terminated by tAVO threads. The OA^aries ai e 
internal, and placed along the sides of the intestinal canal, extending 
from the base of the first pair of feet to the eighteenth ; their open- 
ings appear to be at the root of some of those that are intermediate ; 
the eggs, after having been produced, occupy the dorsal cavity above 
mentioned, and are secured there by means of small threads, Avhich 
adhere to those of the feet. At first they are round and transparent; 
they afterwards assume a yelloAvish tint, Avhich is subsequently darker 
toAvards the centre, and their figure becomes irregular and angular. 
All the individuals examined by M. Ad. Brongniart were proAuded 
Avith them. The males, alloAving the sex to exist, do not aj)pcar at 
the same time as the females, Avhich is during the month of June, and 
are unknoAAm. 
Limnadia Hermani, Ad. Brongn., Mem. du Mus. d’Hist. 
Nat,, VI, xiii ; Daphnia-gigas, Hei'in., Mem. Apterol., V. 
Found in great numbers in the little pools of the forest of Fon- 
tainebleau. 
There, each eye is situated at the extremity of a pedicle, formed by 
a lateral prolongation, in the shape of a horn, of each side of the head. 
The body is naked, Avithout a shell, and annulatcd throughout. The 
* In my work on the natural families of the animal kingdom, this siibgenus, wilh 
that of Apus, composes my family of the Asi)idiphora ; it aj)proximatt's to thio one 
in the number of feet, and to the Dnphnim in the shell, 
