ECHENEIDIFORMES 



449 



Family Echeneididae. The scales are small, cycloid, the suborbital 

 arch slender, the maxilla fixed to the premaxilla. The pectoral fin is 

 placed high up, beneath the disc. The posterior dorsal and anal fins 

 are spineless. There are pyloric caeca, but no air-bladder. The Eocene 

 genus Opisthomyzon has a quite small sucker. 



Opisthomyzon, Cope ; Eocene, Europe. Echeneis, Art., ' Sucking- 

 Fish' ; Bemora, Gill. (Fig. 464) — warm seas. 



Tribe 4. Scorpaeniformes (Scleroparei). 



A natural group of fish, which appear to have been derived from 

 some primitive Perch -like form, and have diverged in several special 

 directions. They are distinguished by the possession of an enlarged 

 posterior suborbital (3rd), which spreads backwards over the cheek (Fig. 

 466), sometimes becoming firmly fixed to the preoperculum (Scorpaena, 

 etc.). This characteristic ' suborbital ' stay is not fully developed in the 

 more primitive genera, and may be again reduced in the more specialised. 

 The parietals often meet in the 

 middle line ; and the gills may 

 be reduced to three and a half. 

 The pectoral radials are gener- 

 ally in the form of flattened 

 plates. 



The fins and scales are 

 generally very spiny, also the 

 head, which tends to become 

 covered with a bony cuirass. 

 Some of the anterior dermal 

 rays of the pectoral fin rest 

 directly on the scapula, with 

 which one or more of the 

 radials seem to have fused 

 (Fig. 467). Whilst about thirty 

 vertebrae occur in the 

 specialised families (Scorpae- 



nidae), the number increases to fifty or sixty in the Comephoridae and 

 Cottidae. 



Sub-Tribe A. The pectoral arch has the perforate scapula and the 

 coracoid normally disposed, and with the latter articulate two of the 

 flattened radials (Figs. 463, 467). 



A. Family Scorpaenidae. The cephalic cuirass is incomplete ; the 

 spinous portion of the dorsal is armed with strong spines, often provided 

 with poison glands, but is not separate. The anal generally has three 

 spines. The cranial bones are usually very spiny, often distorted, and 

 fleshy processes may be developed on the head. The myodome is present. 

 The base of the pectoral fin is broad and vertical, and one or two lower 

 dermal rays may be separate. The radials are constricted. The scales 

 may be lost, and the gills reduced to three and a half, one slit being 



29 



Sebasles percoides, Sol. (After Giinther.) Rigbt- 

 ide view of skull, pr, preopercular ; so, suborbital ; 

 less v '> bony stay from third suborbital. 



