by C. Tate Regan. 209 
P. andersoni, is evidently based on an ambicolorate example of this 
species. Complete ambicoloration in Flat-fishes is usually correlated 
with other variations towards symmetry, such as the delayed or 
arrested migration of the eye, which interrupts the extension forward 
of the dorsal fin, and the similar structure of the scales on both sides 
of the fish. 
2. PsEUDORHOMBUS NATALENSIS. 
Pseudorhombus natalensis, Gilchr., Mar. Inv. S. Afr., IIT, 1905, p: 8; 
pl. xxv. 
Depth of body 2 in the length, length of head 3%. Diameter of eye 
35 in length of head. Maxillary extending to below anterior + of eye. 
Teeth small, forming a close set series in the jaws. Dorsal 70. Anal 
52. Scales ctenoid on left side, cycloid on right, 60 in a longitudinal 
series. Accessory branch of lateral line extending only a little more 
than half way to dorsal fin. Large dark ring-shaped spots symmetri- 
cally arranged on body ; a series of conspicuous spots along dorsal and 
anal fins. 
Natal. 
Here described from a specimen of 135 mm. from off Cape Natal, 
54 fathoms (Gilchrist). 
2. PARACITHARUS, gen. nov. 
(type ARNOGLOSSUS MACROLEPIS, Gilchr.). 
Eyes on the left side, separated by a ridge. Mouth wide; teeth 
small, pointed, in bands in the jaws; no canines; palate toothless. 
Gill-membranes separate. Dorsal fin originating immediately behind 
right posterior nostril, which is large and is covered by a valve that 
extends forward nearly to the mouth. Pelvic fins short-based ; left 
median in position. Scales of moderate size, ctenoid on left side, 
eycloid on the right; lateral line developed on both sides, with a 
strong curve anteriorly ; tubules forked, Y- or T-shaped. 
Citharus, Bleek., with a single species from the Mediterranean, 
differs from Paracitharus especially in the dentition ; the teeth in the 
jaws are uniserial except anteriorly, canines are well developed and 
the vomer is toothed. Also in Crtharus the dorsal originates below 
the posterior nostril and the lateral line tubules are simple. 
