‘EYES OF THE SEROLIDE 359 
water by the character of the eyes. ‘The results,’ he says, 
‘of my investigations into the minute structure of the eye 
in Serolis may be briefly summed up as follows:—(1) The 
shallow-water species invariably possess well-developed 
eyes which are fundamentally similar to those of other 
Isopoda, but differ in several particulars; the retinulee are 
composed of only four cells; the rhabdom is often a highly 
complicated structure unlike that of other Crustacea. 
Another element unrepresented (?) in the eyes of other 
Crustacea is present, consisting of two large hyaline nu- 
cleated cells placed below the rhabdom and between the 
retinal cells. (2) In the deep-sea species the eyes are 
either altogether absent (Serolis antarctica), or, if present, 
show signs of structural degeneration; no retinula, at 
least nothing comparable to the retinula in the eyes of the 
shallow-water species, is present, but the vitreous body is 
represented. ‘The vitreous bodies may be enclosed in a 
sheath of pigment (Serolis neewra), or there may be no 
pigment present (Serolis gracilis, Serolis Bromleyana).’ 
From examination of the contents of the stomachs 
Mr. Beddard has come to the conclusion that these inter- 
esting Crustaceans are upon occasion cannibals. 
Family 5.—Spheromide. 
The body is convex, the head transverse; the pleon is 
vaulted over the pleopods, its earlier segments, exclusive 
or inclusive of the first, being usually fused into a shorv 
segment marked more or less by sutural lines, the terminal 
segment being, on the other hand, very large. The eyes 
are generally wide apart ; both pairs of antennz have the 
flagellum multiarticulate and well marked off from the 
peduncle. The mandibles have a three-jointed ‘palp ;’ 
the first maxille have two plates, the second three; the 
maxillipeds are seven-jointed, the second joint being pro- 
duced into a plate. The limbs of the perzon are slender, 
generally with bifid fingers. The first three pairs of pleo- 
pods are ciliated, with the outer branches not opercular ; 
the second pair in the male have a stilet on the inner 
