EURYDICE PULCHRA. 311 
Tuts beautiful little species was first described and 
figured by Slabber, in his fine microscopical work 
above referred to. His article on it has, however, been 
overlooked by all carcinologists, except Van Beneden, 
who has published a detailed account of it in his re- 
searches on the littoral fauna of Belgium, and who 
remarks that no naturalist had reobserved Slabber’s 
animal; this is not indeed surprising, since the de- 
scription of it by Leach (which has hitherto served for 
all subsequent writers on this tribe) is so short and 
unsatisfactory as not to be readily recognized. 
The body is smooth and of a pale grey colour, each 
segment marked with about eight or ten black dots 
formed of delicate radiating lines, closely resembling the 
markings upon certain varieties of agate; these spots 
are arranged transversely and with a great amount of 
regularity upon the succeeding segments; each of the 
basal joints of the tail, on the other hand, is marked with 
two transverse spots formed of a series of very fine 
black lines; the large terminal segment is transversely 
depressed near the base; the tail is furnished on its 
underside with five pairs of foliaceous membranous plates, 
each articulated across the middle, the basal division 
being almost square, and the apical division nearly semi- 
circular, the latter fringed all round with about twenty- 
five very fine hairs, each of which is fringed along its 
whole length with most delicate cilia; the outer pair of 
the caudal plates do not perform the duty of an opercu- 
lum as in the Idotea, and the sides of the terminal 
segment are furnished with lateral appendages, the outer 
division of each of which is smaller than the inner por- 
tion, which is obliquely truncate at its extremity, and 
hatchet-shaped. 
This species is found in small pools left by the re- 
