BRANCHIOPODA. 
249 
Their eye is small or piinctiform, and, with the exception of certain 
species, has not, as in Lynceus, the small black punctiform spot 
before it, which Muller considered as a second eye*. 
Although the extreme smallness of these animals might be supposed 
to defy any attempt to investigate their organization, but few are 
better known. Exclusive of those who have devoted themselves to 
microscopic researches, four of the most profound naturalists, 
Schaeffer, Randohr, Straus, and Jurine, Sen., the third particularly, 
have studied them with the most scrupulous attention. If some 
anatomical details escaped the notice of the latter, the omission has 
been remedied by the labours of Randohr and Straus; Jurine also 
completes the observations of the former with respect to their habits, 
which he studied fora long period, and with the greatest success. The 
mouth is situated beneath at the base of the rostrum; we consider (with 
Randohr) the inferior portion of the head, which Straus denominates 
a labrum, as an elongated clypeus, and we apply the former term to 
that part which he styles the posterior lobule of the labrum. Directly 
under it are two strong jaws — interior jaws of Randohr — without 
palpi, vertically inclined, and applied to two horizontal jaws f termi- 
nated by three stout horny spines, in the form of recurved hooks. 
Then come ten feet, the second joint of all of which is vesicular ; the 
first eight terminate by an expansion in the manner of a fin, the 
edges furnished with setse or barbed threads arranged like a crown or 
a comb ; the two anterior seem to be specially appropriated to the 
purposes of prehension, and in fact Randohr considers them as double 
palpi, the external and internal ; they are the same parts, elsewhere 
— Cyclops — called hands by Jurine. In the figures which they have 
published, the terminal setae appear to be bearded ; if this be so, we 
do not see why these appendages may not concur in the process of 
respiration J, a property confined by Straus to the following ones, 
because the latter have, besides, a lamina on the inner side, which, 
with the exception of the two last, is edged with a pectinated series 
of setae, that according to the figures of Jurine and Randohr are also 
bearded. The structure of the two last feet is somewhat different, 
and Randohr distinguishes them by the name of claws. The abdo- 
men, or body properly so called, is divided into eight segments 
perfectly fi’ee between its valves, and is long, slender, recurved at 
the extremity, and terminated by two small hooks directed backwards. 
On the superior surface of the sixth segment is a range of four 
papillae forming indentations, and the fourth presents a sort of 
* Such also is the opinion of Randohr, Monoc. pi. V, fig. II, iii, 6 ; and as he 
discovered it in the Daphnia sima, it is possible that, although but slightly visible 
in several species, this character may be common to this subgenus, and that of 
Lynceus. Schfefter had previously noticed it. 
-f- The exterior jaws, in the language of Randohr ; Jurine not having separated 
these parts from the preeeding ones, supposed that the latter were accompanied by 
a kind of valve and by a palpus. Hist, des Monoc. IX, f. 1.3 — 17. 
X According to Straus, Cypris and Cythere are not true Branchiopoda, inasmuch 
as their feet are not provided with branchipe ; but, as we have already observed, the 
setfc and hairs of the two anterior ones and those of the antennse may e.xercisc the 
functions of branchia: as well as those of the palpi and first jaws. 
