BRITISH HYDRA CHNID.?*:. 147 



Nes^a Longicornis. 



1834 — 41. — Nescea longicornis, C. L. Koch, Deidschlands Crust., 



etc., p. 9, Figs. 14 and 15. 



Koch gives, in his Ubersicht, Nescea rosea as his type of Nescea 

 (see Fab. I., Figs. 2 and 3). I have described and illustrated 

 Nescea longicornis because I happen to have a male and female of 

 the same species. I have found several males of Nescea, but am 

 at present uncertain with which females to pair them off. Mliller 

 also figures longicornis on Twb. IV.. Fig. 4, and describes it on 

 page 47. Newman also gives N. longicornis, but I am not certain 

 if it can be the same as the one described by Koch. N. longicor- 

 nis is pale yellow in colour, with dark brown patches on the dorsal 

 side, and a red Y-shaped mark in the centre, extending from just 

 behind the eyes to the posterior margin ; in Koch's figure this 

 mark is very plainly shown. 



The first three joints of the legs, counting from the body, are 

 pale yellow, which gradually turn to a pale blue on the last three 

 joints, those of the male and female being the same in this 

 respect. The body of the female is oval in shape. The legs are 

 very much alike. The epimera (see Fig. 2) are wide apart. The 

 body of the male is flattened on each side and bent inwards on 

 the anterior margin. The epimera of the third and fourth pairs 

 of legs are close together ; they very nearly, but do not quite 

 touch (see Fig. i, a). Close to the posterior margin of the 

 epimera is the genital fissure ; the third pair of ungues of the 

 males are more often than not firmly hooked into this part. I 

 have endeavoured to show this on one side of Fig. i, a. The 

 fourth leg is very peculiar (see Fig. i, d). The length of the body 

 of the female is 1 3/1 50th of an inch, that of the male being 

 i9/3ooth, 



EXPLANATION OF PLATE VI. 



Fig. 1. — Dorsal view of Nescea longicornis, male. 



,, 1, a. — Ventral view of same, showing on one side the way the 

 third pair of feet are held in the genital opening. 



,, 1, b. — Genital area of male. 



,, 1, c. — Third leg of ,, 



