840 



NORTH AMERICAN INDEX FOSSILS. 



Manasquan — upper Cretacic of Atlantic 

 coast. 



Mandibles — the first upper or outer pair 

 of jaws of crustaceans and insects. 



Manitou limestone — lower Ordovicic of 

 the Rocky Mountain front range. 



Mansfield sandstone — Carbonic of In- 

 diana. 



Mantle — the fleshy membrane infolding 

 the soft parts of mollusks and brach- 

 iopods and building the shell. In 

 cephalopods, see Fig. 1230. 



Manzano group — upper Carbonic of 

 New Mexico, etc. 



Maquoketa formation — upper Ordo- 

 vicic of upper Mississippi Valley. 



Marcellus shale — middle Devonic of 

 eastern North America. 



Marion formation — subdivision of the 

 Sumner (Permic) of Kansas. 



Mariposa formation — upper Jurassic of 

 California. 



Mark's Mill beds — upper Eocenic of 

 Arkansas. 



Marmaton formation — middle Carbonic 

 of Kansas. 



Marshalltown formation — middle Cre- 

 tacic of Atlantic coast. 



Martinez group — lower Eocenic of Pa- 

 cific coast. 



Marysville limestone — middle Cambric 

 of southern Appalachians, 



Matawan formation — middle Cretacic 

 of Atlantic coast. 



Matthews landing beds — lower Eocenic 

 of Alabama. 



Mauch Chunk red shale — upper Missis- 

 sippic of the Appalachians. 



Maxilla — one of the two pairs of jaws 

 in crustaceans and insects (see II., 

 387). 



Mayville limestone — basal Niagaran of 

 Wisconsin. 



Maysville beds — middle division of Cin- 

 cinnati group, upper Ordovicic (= 

 Lorraine). 



Maxilliped — in Crustacea, the jaw-feet 

 (see II., 387, and Fig. 1692). 



Maxville limestone — upper Mississippic 

 of Ohio. 



Mazon Creek beds — middle Carbonic 

 (Alleghenian) of Illinois. 



Meadville shales and limestones — lower 

 Mississippic of western Pennsylvania. 



Media — in insects, one of the wing veins 

 (see Fig. 1724). 



Medial — middle. 



Median — middle. 



Median fold — see fold. 

 Median sinus — see sinus. 



Medina sandstone — basal Niagaran of 

 western New York. 



Medusa — a jelly fish. 



Meekoceras beds — lower Triassic of the 

 Pacific region. 



Membranaceous — pertaining to or con- 

 sisting of membrane, 



Mendota beds — upper Cambric of Wis- 

 consin. 



Meramec group — general term for the 

 middle Mississippic. 



Merced series — Pliocenic of Pacific 

 coast. 



Mercer beds — upper Kanawha of Ohio, 

 etc. 



Merchantville beds — middle Cretacic of 

 Atlantic coast. 



Mero-plankton — an organism which 

 during its larval stage drifts aim- 

 lessly (planktonic), but later settles 

 to the bottom and becomes benthonic. 



Meropodite — see II., 388. 



Mesenteries — in corals, one of the verti- 

 cal membranous partitions projecting 

 inward from the body wall and divid- 

 ing the gastric cavity into a series of 

 radiating compartments, each of 

 which is continuous with the cavity 

 of the tentacle above. In forms se- 

 creting radiating septa, the mesen- 

 teries are in pairs, each pair enclos- 

 ing a septum which is secreted by the 

 upward bent portion of the ectoderm 

 beneath. 



Mesial — middle. 



Meso — a prefix, signifying in the mid- 

 dle ; frequently used in contradistinc- 

 tion to meta, behind, and pro, before. 

 For use in insects, see II., 420. 



Mesoderm — the middle body layer. 



