1006 CLASS PISCES. 



pleurns, of the European Chalk, with which the North American 

 genus Syllcemus is probably identical, may be placed in this 

 family. 



Family Atherinid/e. — These fishes, which differ from the 

 Mullets by the presence of an indistinct lateral line and the great 

 number of the vertebrae, are represented in the Middle Eocene of 

 Monte Bolca by two minute species of the existing genus Athe?-ina, 

 and also by the extinct Mesogaster. 



Family Sphyr^enid^:. — The Barracudas, in which the lateral 

 line is continuous and the vertebrae are not numerous, are known 

 at the present day only by Sfihyrcena, of which some species attain 

 a length of eight feet. That genus occurs in the Middle Eocene of 

 Monte Bolca, and has also been recorded from the Upper Creta- 

 ceous of the Lebanon ; but it is probable that the latter form belongs 

 to one of the Saurodont Physostomi. Cladocydus, from the Upper 

 Cretaceous of England and Brazil, is an extinct genus. 



Family BLENNiiDiE. — The Blennies form one of four families of 

 but little palaeontological importance, in which there is a long dorsal 

 fin, which may be entirely spinous ; and the ventrals, if present, are 

 either thoracic or jugular. It is probable that Pterygocepkalus, from 

 the Middle Eocene of Monte Bolca, should be referred to this 

 family. 



Family Gobiid^e. — The Gobies belong to another group of the 

 suborder comprising two families, into the characters of which it 

 will not be necessary to enter. They are represented in a fossil 

 state by the existing genus Gofo'us, from the Monte Bolca Eocene, 

 and the extinct Chirothrix, from the Upper Cretaceous of the 

 Lebanon. 



Family Dactylopterid^e (Cataphi-acti). — This and the next six 

 families form a group of considerably more interest to the palaeon- 

 tologist than the preceding. They are collectively known as the 

 Cottoscombriform section, and are characterised by the presence of 

 spines in at least one of the fins ; by the dorsal fins being either 

 continuous or close together ; by the spinous dorsal, when present, 

 being short ; and when the latter is absent by the length of the soft 

 dorsal. The pelvic fins are always jugal or thoracic. In the present 

 family the body is cylindrical and elongate, with a coat of bony 

 scutes ; the dentition is weak ; and the pelvic fins are thoracic. 

 Petalopteryx, from the Middle Eocene of Monte Bolca, is considered 

 to be related to the existing Dactylopterus, in which the pectorals 

 are lengthened to an enormous extent. 



Family Cottid^e. — This family is best known by the freshwater 

 Bull-heads (Coitus) and the marine Gurnards (Trig/a). The body 

 is more or less oblong ; the dentition weak ; the dorsal fin is usually 

 divided, with the soft portion the larger; and the pelvic fins are 



