BRANCHIOPODA. 44 1 
' varying; according to the length of their oars and the breadth of their shells. According to Strauss, their food con- 
sists exclusively of minute particles of vegetable substances, which they meet with in the water, and often of 
confervas. They constantly refused the animal matter he gave them. It is by the action of their legs that they pro- 
duce a current on the water, which brings their food towards the mouth. The hooks at the tip of the tail are 
used in cleaning the branchiae. [Mr. Baird has published a detailed account of the anatomy and habits of this 
genus in the second volume of the Magazine of Zoology and Botany.'] 
The most common species is D. pulex, {Monoculus pulex, Linn. ; Pulex aqiiaticus arbor escens, Swammerdam), 
or the arborescent water-flea. It has the setae of its oars plumose ; its valves are notched on the lower edge, and 
terminated by a short tail, which is obtuse in the females. 
The last subgenus is Lynceus,MvL\\&c (Chilodorus, Leach), distinguished by the oars being shorter than the shell, 
and of which the lower part does not form a produced point. All the species have in front of the eye a small 
black spot, having the appearance of a second [frontal] eye. 
The second section of the BrancMopoda — that of the Phyllopa— is distinguished from 
the former by the number of feet, which is at least twenty,* and in some much more con- 
siderable ; their joints, or at least the terminal ones, are flattened, lamellar, or foliaceous, and 
ciliated. The mandibles are destitute of palpi. They have two eyes, (situated in some at 
the extremity of two moveable peduncles,) and some have also an ocellus ; the antennae, of which 
there are generally only two, are small, and not fitted for swimming. These Crustacea compose 
' two principal groups. 
' 1. The Ceratopfhalma, Latr., have at least ten pair of legs, and at the most twenty-two pairs, 
jl . 
:i without any vesicular appendages at their base, and of which the anterior are never much longer than 
‘ the others, nor ramified. The body is inclosed in a shield, formed like a bivalve shell, or naked, with 
|| each of the thoracic divisions bearing a pair of exposed feet. The eyes are sometimes sessile, small, 
Ij and close together, but more commonly they are situated at the extremity of two moveable peduncles. 
i| The eggs are internal or external, and inclosed in a capsule at the base of the tail. 
! In some species the eyes are sessile, immoveable, and the body inclosed in a bivalve shell ; the 
I ovaries are always internal. They form the genus 
I Limnadia of Ad. Brongniart, which so nearly approach the preceding that Hermann placed the only species 
j known [to him and Latreille] amongst the Daphnise. The shell is oval, bivalve, and incloses the body, which is 
long, linear, and inflected in front. Upon the head are placed, 1, two eyes in a transverse direction, and close to- 
ll gether ; 2, four antennae, two much longer than the others, each composed of an 8-jointed peduncle, and two 
ij 8-jointed setaceous branches, rather silky, and two others intermediate in situation, small, simple, and dilated at 
j the tips; 3, the mouth, situated beneath, consisting of two mandibles, swollen, curved, and truncate at the 
Ij inferior extremity, and two foliaceous maxillae. These parts form together a kind of beak, placed beneath. The 
body, properly so called, is divided into twenty-three segments, each of which (except the last) bears a pair of 
I branchial feet. All these feet are alike, very compressed, bifid, with the outer division simple, ciliated at the 
jl outer edge, and the other 4-jointed, and strongly ciliated on the inner edge. The twelve fore pairs of legs are of 
:j the same length, and longer than the others, which diminish gradually in length. The eleventh, twelfth, and 
f thirteenth pairs have at the base a slender filament, bent upwards into the cavity between the back and the shell, 
1 serving as the support for the eggs. The ovaries are internal, and situated at the sides of the intestinal canal. 
|j Tine eggs, after being laid, occupy the dorsal cavity above noticed, and are there attached by means of small fila- 
I ments adhering to those of the supports. They are at first round and transparent, but afterwards become 
i darker, and irregular in shape. All the individuals observed by Brongniart were provided with them, so that the 
il males remain unknown (if there are individuals of that sex), and are supposed to appear at a different season from 
|i the females. The type, Limnadia Hermanni (A. Brongniart, Daphina gigas, Hermann), has been found in small 
i| pools of water in the forest of Fontainebleau. 
jj [M. Guerin has published a monograph upon this genus in his Magasin du Zoologie for 1837, describing three 
I species.] 
\Estheria, Strauss, {Cyzycus, Audouin,) is a genus closely allied to Limnadia, found in the Red Sea. Type, B. 
[I Dahalaeensis, Ruppell, in Trans. Mus. SecJtenberg, 1837.] 
In the other species of Ceratopthalma, the eyes are placed at the extremities of two long peduncles, 
formed by the lateral prolongation, like a nose on each side of the head. The body is naked, not in- 
closed in a shield, and annulated throughout its entire length. The females carry their eggs in an 
elongated capsule, placed at the base of the tail when present, or at the posterior extremity of the body 
and thorax in those which have no tail. 
Artemia, Leach, has the body terminated by a tail, the eyes borne at the extremity of very short peduncles ; 
the head confluent, with an oval thorax, supporting ten pairs of legs, and terminated by a long and pointed tail. 
* These animals represent in this class of Crustacea the M}'riapo(la in that of the Insecta. 
