688 TELEOSTEI CHAP. 
aberrant group. The strongly compressed body is covered with 
minute, rudimentary scales; the dorsal is short, with few, 
graduated spines, and the anal much elongate, with 2 small 
spines; the ventrals are formed of 1 spine and 5 soft rays. 
The vertebral column consists of 24 vertebrae; the ribs of 
the third and fourth are free and slender, whilst the following 
Fia. 419.—Skeleton of Aurtus indicus. 
are immovably fixed between rings formed by the ossification 
of the outer membrane of the elongate air-bladder in a manner 
unique among fishes. The skull is peculiar for its very strong, 
denticulate, occipital crest, which ends posteriorly in a curved 
spine bent forwards; the suborbitals are slender and do not 
emit a subocular lamina. Kurtus indicus does not exceed a 
length of 5 inches. 
Division V.—GOBIIFORMES. 
No bony stay for the praeoperculum. Basis cranii simple. 
Spinous dorsal, if present, formed of few, flexible rays. None 
of the epipleural bones attached to the centra of the vertebrae 
in the praecaudal region. Scapula and coracoid more or less 
reduced or even vestigial; pterygials large, 4 or 5 in number, 
forming together a thin plate which is in contact with or 
narrowly separated from the clavicle; one or two of the ptery- 
gials in contact with the coracoid. Ventral fins thoracic. 
The Gobiidae, which alone constitute this division, are not 
very remote from the Perciformes, and may have evolved out of 
a type not very different from the Percidae. 
