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. 7:,) 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. 1, f, f,) 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, + 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. Albidiis, 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 et rubro." — Midler, p. 112. 



