LVNCEIDiE. 
117 
mation till Milne Edwards published his work on the 
Crustacea in 1840.* In this work the author shows 
the necessity for breaking down this heterogeneous genus, 
and reforming it ; but he does not make the attempt 
himself, nor do I know of any attempt having been made 
before I published my paper on the Lynceus, in the 
‘ Annals and Magazine of Natural History/ 
Anatomy and Physiology , 8fc . — In general formation 
the animals of this family are very much like the 
Daphniadae; the most remarkable points of difference 
being the shape of the head and beak, and a small black 
spot a little distance from the eye, much smaller than it, 
which is considered by Muller as a second organ of vision, 
and from which he has given the name to the genus. f 
The shell or covering which incloses the body does not 
consist of two distinct and separate valves, but is open 
only on the anterior margin, and for a portion of the 
posterior extremity. The part which we may call the 
head is harder than the other portion of the shell, and is 
prolonged in most of the species into a sharp and very 
distinct beak. Belonging to it we find, besides the beak, 
the eye with its accompanying black spot, the superior 
antennae, the inferior, or rami, the brain, mouth, and 
part of the digestive canal. 
The eye (t. XV, f. 11), as in the Daphniadae, is a 
spherical body contained in a somewhat funnel-shaped 
sheath of muscles, having a semirotatory motion, and 
consisting of a series of crystalline bodies ; which, in the 
Eurycercus lamellatus, are about twenty in number. 
The black spot, which Muller considers as a second eye, 
is situate before, and at a little distance from, the real 
eye, generally near the end of the beak, almost at the 
extremity of the body of the animal, and near the root 
of the antennae. It is much smaller than the eye, has no 
* Hist. Nat. des Crust., vol. iii. 
f “Nomen Lyncei in Zool. Dan. prod, ex punctis binis oceUaribus, quae 
organa visus absque dubio sunt, indixi.” — Entomost., p. 67. 
