842 



NORTH AMERICAN INDEX FOSSILS. 



beak to beak, as in Area and Perna. 



Mural — pertaining to a wall. 



Mural pores — pores in the walls of 

 the corallites of the Favositidse (see 

 Fig. 139). 



Muscle scar — the scar in a shell mark- 

 ing the former attachment of a mus- 

 cle. For application in brachiopods 

 and pelecypods, see also adductor, di- 

 ductor. In cephalopods, see II., 18. 



Naco limestone — Carbonic of Arizona. 



Nacreous — pearly ; the nacreous layer 

 in shells is the inner smooth " mother 

 of pearl " layer. 



Nahant formation — lower Cambric of 

 eastern Massachusetts. 



Nanafalia formation — lower Eocenic of 

 Alabama. 



Nanaimo group — lower Cretacic (Colo- 

 radoan) of Vancouver Islands. 



Nanjemoy formation — subdivision of 

 the Pamunkey (lower Eocenic) of 

 Atlantic coast. 



Naples beds — local division of the Por- 

 tage (upper Devonic) of New York. 



Nashville group — upper Ordovicic of 

 western Tennessee. 



Nasute — projecting nose-like, 



Naticoid — like Natica (see I., 588, C, 

 and I., 717, and Fig. 1038). 



Nautilicone — closely coiled Nautiloid 

 cephalopod shells, with impressed 

 zone (ex. Nautilus) ; see Fig. 1335. 



Nautiliform — coiled like Nautilus or 

 like Bellerophon (see I., 619, Figs. 

 830, 1335). 



Navarro formation {Eagle Pass) — up- 

 per Cretacic of Texas. 



Navesink marls — middle Cretacic (Mon- 

 mouth) of Atlantic coast. 



Neanic — youthful (see ontogeny). 



Nebo sandstone — lower Cambric of 

 southern Appalachians. 



Neck furrow — see occipital furrow. 



Neck ring — see occipital ring. 



Neelytown limestone — uppermost Cam- 

 bric of eastern New York (Sarato- 

 gan). 



Nekton — an organism which leads an 



actively swimming life. 

 Nepionic — infantile (see ontogeny). 

 Nettle-cell — in most Coelenterata, one 



of the nematocysts or stinging cells 



found covering the tentacles and 



other body parts. 

 Nevada limestone — Devono-Mississip- 



pic of Nevada. 

 New Albany black shale — upper De- 

 vonic of Indiana, etc. 

 Newark system — continental Triassic 



of eastern North America. 

 Nezvman limestone — middle Mississip- 



pic of southern Appalachians, 

 New Scotland beds — a division of the 



Helderbergian (lower Devonic). 

 Niagaran — general term for the lower 



Siluric. 

 Nichols shale — lower Cambric of south- 

 ern Appalachians. 

 Nidamental glands — those glands in 



cephalopods which secrete the sticky 



substance for cementing the eggs 



together (see Fig. 1230). 

 Niobrara series — lower Cretacic (Colo- 



radoan) of Great Plains region. 

 Node — a knob. In gastropods, see I., 



583. In crinoids, see II., 488. 

 Nodose — bearing nodes or tubercles. 

 Nodulose — knotty or having nodes. 

 Noel black shale — see Eureka black 



shale. 

 Nolichucky shale — middle Cambric of 



southern Appalachians. 

 Non — a prefix, meaning not. 

 Noric — division of the upper marine 



Triassic. 

 Normanskill shale — middle Ordovicic 



of Hudson Valley, etc. 

 North Attleborough limestones — lower 



Cambric of southeastern Massachu- 

 setts. 

 Notch — for anterior and posterior notch 



in gastropods, see L, 583- 

 Notum — in insects, the tergum (see II., 



420). 

 Nummuloidal — in cephalopods, applied 



to the siphonal funnel when swollen 



