Lophohranchii and Plectognathu 45 



at Monte Bolca. Acanm is an extinct genus, originally referred to 

 the Berycidae, from the Eocene Slates of Canton Glaris, Switzerland. 

 The " Bass" (Labrax) occurs in the Monte Bolca deposits. Of the 

 Perch (Perca) there are extinct species in the Upper Eocene of Aix 

 in Provence, and the Miocene lignites of Central France, in addition 

 to a very large form (Perca lepidota) from the Miocene beds of 

 Oeningen, Switzerland. Paraperca, from Aix, is also a closely 

 allied form. 



Suborder V. — Lophobeaxchii. 



These are a small suborder of Teleostean fishes having the gills 

 not laminated, but in the form of small rounded lobes or tufts. 

 The gill-cover is reduced to a large simple plate ; and the body is 

 more or less encased in hard scales, arranged in segments. 



Here are placed the "Pipe-fishes" and " Sea-horses, " which Table-case, 

 have but few fossil representatives. An extinct species of No. 56. 

 Siphonodoma is exhibited from the Miocene of Licata, Sicily ; and 

 there is also an ancient type of "Sea-horse" — Calamostoma — 

 differing from the living Hippocampus in the possession of a caudal 

 fin, from the Eocene of Monte Bolca. Another " Pipe-fish," 

 Sohnorhynchus, has been found in the Eocene of Monte Postale. 



Suborder VI. — Plectogxathi. 



Like the preceding suborder, the Plectognathi are remarkable for 

 their dermal skeleton, and both these groups were originally placed 

 by Agassiz among the Ganoids, on account of the characters of 

 their armour. Some of these fishes (e.g. Ostracion) have the 

 integument converted into a continuous mosaic of hexagonal scutes ; 

 in others (e.g. Diodon) the skin is covered with numerous isolated 

 spiny ossifications ; while others are almost destitute of hard dermal 

 structures. The pelvic fins are either absent or merely represented 

 by spines ; and the bones of the upper jaw are nearly always firmly 

 united. 



Fig. 81. — Teeth of Liodon Scillce, Miocene, Malta. 



The suborder is divided into the two families of Sclerodermi and 

 Gymnodontes, the former of which have the jaws armed with dis- 

 tinct teeth, while the latter are provided with a kind of edentulous 

 beak. Fossil Scleroderms, in an excellent state of preservation, Table-case 

 are found in the Eocene Slates of Glaris, where two extinct genera, No. 56. 



