XXIII ACANTHOPTERYGII 687 
characters which the examination of a large number of generic 
types shows not to be constant. Thus the former have been 
defined as having the praeopercular margin distinct externally, 
the snout not projecting beyond the mouth, the nostrils of the 
two sides on the coloured side or those of the blind side high 
up near the dorsal line of the head; the latter as having the 
praeoperculum hidden under the skin, the snout projecting more 
or less beyond the mouth, and the nasal organ of the blind side 
similarly situated to that of the eyed side. However, the genera 
Aphoristia and Peltorhamphus, and others among the Soles, show 
exceptions to this definition.’ 
Principal genera: Psettodes, Atheresthes, Platysomatichthys, 
Hippoglossus, Hippoglossoides, Hippoglossina, Poecilopsetta, Chas- 
canopsetta, Paralichthys, Pleuronectes, Glyptocephalus, Citharus, 
Lhomboidichthys, Psetta (Rhombus), Arnoglossus, Zeugopterus, 
Lepidorhombus, Ammotretis, Rhombosolea, Solea, Achirus, Achir- 
opsis, Soleotalpa, Synaptura, Ammopleurops, Aphoristia, Cyno- 
glossus, Symphurus (Plaqusia). 
The following are the principal British representatives which 
are valued as food :—The Hahbut (Hippoglossus vulgaris), by far 
the largest of all Flat-Fishes, growing to a length of 10 feet or 
more; the Long Rough Dab (Hippoglossoides limandoides) ; the 
Plaice (Pleuronectes platessa); the Flounder (P. flesus), which 
ascends streams; the Dab (P. limanda); the Smear Dab, often 
called Lemon Sole (Glyptocephalus microcephalus); the Witch 
(G. cynoglossus); the Megrim or Whiff (Lepidorhombus mega- 
stoma); the Turbot (Psetta maxima); the Brill (P. laevis); and 
the Sole (Solea vulgaris). 
Division I1V.—KURTIFORMES. 
No bony stay for the praeopercle. Dorsal spines feeble, few. 
Scapula absent, the coracoid supporting four small pterygials. 
Ventral fins thoracic. 
Fam. 1. Kurtidae.—The genus Aurtus, with a single species, 
from the Indian and Pacific Oceans, forms an isolated, very 
1 On the morphology and classification, cf. Traquair, 77. Linn. Soc. xxv. 1865, 
p. 263 ; Jordan and Goss, Rep. U.S. Fish Comm. f. 1886 (1889) ; Kyle, Rep. Fish. 
Board Scotland, 1900, p. 335. Also the Monographs of the Sole, by J. T. Cunning- 
ham (Plymouth, 1890, 4to), and of the Plaice by Cole and Johnstone, Liverpool 
M.B.C. Memoirs, viii. 1901. 
