146 BRITISH HYDRACHNID^. 



yellow colour. This film was covered — or at least appeared to be 

 so — with little cracks ; it was firmly attached to the glass. Fig. 3, a, 

 shows the appearance of two eggs under a higher power. There 

 were sixteen eggs in this one group. Each egg seemed to have its 

 own share of film, although all were in one mass. The eggs gra- 

 dually altered from circles to ovals, until on May the 24th they 

 had the appearance of Fig. 3, b. It will here be noticed that the 

 red portion of the little egg had begun to contract at each end. 

 On May 28th they had the appearance of Fig. 3, c. On May 30th 

 the eyes in some cases could be seen quite plainly (Fig, 3, d). 

 On May 31st the shape of the little creature could be distinctly 

 made out (Fig. 3, ^) ; a constant movement of the limbs could be 

 plainly seen. The delicate membrane in which the eggs were laid 

 was also cracked all over in a very marked manner, no doubt for 

 the purpose of letting the little creatures escape. On the morning 

 of June the ist, when I examined them, some three or four of the 

 larvae had escaped and were swimming freely about. When I 

 looked again in the evening, all were out swimming vigorously. 



Fig. 3, g, is drawn from the ventral side of one of the larvse 

 three days after it was hatched. How long they live in this form 

 I cannot say. I placed all when hatched in a small tank with 

 nothing but vegetable life, and found them alive on June the 20th. 

 The larva is a pale yellow colour, with a bright red, double cres- 

 cent-shaped patch on the body, as shown in Fig. 3, / the shaded 

 portions representing the red colour. This is as far as my own 

 observations at present have gone with the larva of Nescea. 



Genus IV. — Nes^a (Koch). 



1842. — C. L. Koch, Ubersichi des Arachnidensy steins, No. 3, p. 10. 



Body, soft skinned ; legs well supplied with swimming hairs ; 

 claws to all tarsi. The tarsi and ungues of the male, and the third 

 and fourth pairs of legs specially modified. On each side of the 

 sexual fissure are six or more so-called genital pores, either sunk 

 into the skin or on special plates. The epunera form two separate 

 groups on each side. Palpi not chelate ; mandibles in two dis- 

 tinct portions ; eyes wide apart. 



