History of British Entomostraca. 323 
internal side, a tubercle from which issues a plumose spine ; the 
third, the smallest, consists of three parts, the middle piece trian- 
gular-shaped, divided into two strong spines ; the internal, situate 
at its root, giving origin to a long and strong spine, which, near the 
middle, gives off another ; and the external, which is cleft into two 
strong spines. These five strong spines are called fingers by Jurine, 
but, as represented in the accompanying plate, sketched as they oc- 
curred to me, they differ very widely in appearance from the fingers 
represented by him in his figure of these organs ; * and though most 
of the other parts of the insect, as given in his plates, are very cor- 
rect, I cannot help thinking, however much indebted we may be to 
the fair artist, that the representation of these parts borrows a good 
deal from Mademoiselle Jurine's imagination. Feet (Fig. 1, e, 
Fig. 7j) eight in number, or four pairs ; each foot is double, or com- 
posed of two stalks arising from a common base ; each stalk consists 
of three articulations, and each articulation is furnished with plu- 
mose setae, the terminating one having six or seven. The first pair 
of feet do not differ from the rest. First ring of tail is very small. 
In the male (Fig- 13,) the second ring is the largest, while in the 
female (Fig. 1,) it is the third. The last gives off two long lobes, 
making the tail appear bifurcated, each lobe giving origin to four 
plumose setae, the two intermediate of which (Fig. l,^./,) are 
much the longest, and have near upper extremity a small joint, 
which adds much to the suppleness of these fine organs. The fulcra 
or supports, in this species, are very small. Male organs of gene- 
ration (Fig. 13, a, a,) are two oval bodies, situate on each side of 
second articulation of tail, and terminating in a prolonged point. 
Internal ovaries (Fig. 14, a, a,) pretty large and divaricate. Ex- 
ternal ovaries (Fig. 3,) of same colour as adult, and containing in 
an old female thirty or forty eggs on each side. 
Jurine makes five distinct varieties of this species,t three of which 
I have frequently seen in this country. 1. Rubens, 7-12ths of a line 
long without the tail filaments ; of a reddish colour ; external ova- 
ries of same colour as adult animal, (Fig. 14,) 2. Albidus, 8-12ths 
of a line long ; of a light-grayish colour ; external ovaries nearly at 
a right angle with tail, (Fig. 3 ;) body more rounded than in Ru- 
bens ; male one-third less than female. 3. Viridis (Fig. 1,) 9-12ths 
of a line long ; largest of all the varieties ; of a green colour, more 
* Plate 2, Fig. 6, 7 The figure of these organs, as given by Ramdohr, 
tab. ii. fig. 2, of his work, though not altogether correct, is much nearer the 
truth than that of Jurine. 
f " Variat colore albida, fulvescente, viridi ct rubro." Muller, p. 112. 
