576 MANUAL OF NATURAL HISTORY. 



Perdix; the grallatorial genera of Tantalus, Scolo- 

 pax, and Nume&ius, and the natatorial Carbo, or 

 Cormorant. In the eocene of Sheppey, an extinct 

 raptorial bird, allied to the vultures (Lithornis), 

 and another departed form allied to the King- 

 fishers (Halcyornis) have been discovered ; and in 

 the schists of Glarus, an extinct genus of incessorial 

 birds, the Pyctornis. Among reptilian forms, nearly 

 perfect carapaces of turtles and tortoises have been 

 found in the eocene strata of Hampshire and the 

 Isle of Wight ; an extinct genus of serpents, Palce- 

 ophis, has been discovered in the sand of Kyson, 

 together with species of the fresh -water tortoises, 

 Emys and Platemys. The fishes of this group com- 

 prise seven extinct genera of Placoids, belonging to 

 the family of Chimceridce; a single fossil Diodon ; 

 and several genera, mostly extinct, of the Ostra- 

 ciontidcB. In Mollusca, extinct species of existing 

 genera are very numerous in the marine deposits of 

 the tertiary strata ; two hundred and twenty fossil 

 species of Cerithium alone having been identified, 

 besides numbers of Pleurotomia, Fusus, and Buc- 

 cinum. A few extinct genera also occur, as Pile- 

 olus, Omalaxis, and Pleurotomaria. But few spe- 

 cies of Helicidce have been found ; only ten species 

 of Patella; one Haliotis ; about seventeen Neri- 

 tince; numerous Trochidce; nineteen Cowries; and 

 many species of cones, helmet-shells, rock-shells, and 

 tritons. Among Pteropods, a few extinct forms 

 occur , two fossil species of Cavolina are found in 

 the tertiary beds of Dax and Turin. Nearly a 



