AIR-BREATHERS OP THE COAL PERIOD. 283 



and deeply sunk in the jaw. Length of lower jaw 1.3 inch 

 Bones of skull puncto-striate. Limbs unknown, probably natatory. 



Skdis InCERTjE. 



Genus. — E os aurus. 



Eosaurus Acadianus, Marsh. — Known by two biconcave ver- 

 tebrae 2.4 inches in diameter and much resembling the caudal 

 vertebrae of Ichthyosaurus — see paper by Mr. Marsh, Silliman's 

 Journal, vol. xxxrv. 



Province.— ARTICULATA; 



Sub Class. — Myriapoda, 

 Order.— Chilognatha. 



Genus . — Xylo bius . 



Xylobius Sigittarim. — Dawson. — Body crustaceous, elongate,, 

 one to two inches in length, articulate ; when recent, cylindrical o r 

 nearly so, rolling spirally. Feet small, numerous ; segments 30 or 

 more ; anterior segments smooth, posterior with transverse 

 wrinkles, giving a furrowed appearance. In some specimens 

 traces of a series of lateral pores or stigmata. Labrum ? quadri- 

 lateral, divided by notches or joints into three portions. Mandibles 

 two-jointed, last joint ovate and pointed. Eyes ten or more on 

 each side. 



Province.— MOLLUSCA. 



Class. — GaSTEROP ODA . 

 Order. — Pulmonata, 



Genus, — Pupa. 



Pupa Vetusta. — Dawson. — Cylindrical, tapering toward the 

 apex ; surface shining, minutely marked with longitudinal ridges ; 

 whorls 8 or 9, rounded, width of each equal to half the diameter 

 of the shell ; aperture rather longer than broad ; outer lip regu- 

 larly rounded and somewhat reflected ; pillar lip straightened above, 

 rounded below. Edentulous or with faint ridges on columella I 

 Length .3 inch or a little more. 



