GLOSSARY, 



841 



Mesopore — in Bryozoa, one of the small- 

 er, angular or irregular tubes occupy- 

 ing the space between the normal 

 larger ones (zoecia), 



Mesotheca — the " middle wall " result- 

 ing from the growing together of the 

 epitheca of two parts of a bryozoan 

 colony. 



Mesothorax — see II., 420. 



Meta — a prefix, frequently used in zool- 

 ogy as indicating posterior (see 

 me so). 



Metamorphosis — a change in the form 

 or function of an organism by a nat- 

 ural process of growth or develop- 

 ment. In insects, this change takes 

 place suddenly, as from the larval or 

 caterpillar stage to the butterfly, and 

 is hence very noticeable. 



Metastome — underlip of Crustacea, 

 composed of small pieces immediately 

 below and behind the mouth. Very 

 seldom preserved in trilobites ; it is 

 just posterior to the hypostome. 



Metathorax — see II., 420. 



Micro — a prefix, meaning small. 



Microcorallites — the smaller corallites 

 of a compound corallum. 



Midwayan — lower Eocenic of the Gulf 

 coast. 



Millsap limestone — Mississippic of 

 Front Range of Colorado. 



Milwaukee dolomite — middle Devonic 

 of Wisconsin. 



Mimoceracone — a loosely coiled Am- 

 monoid shell (see IL, 19). 



Missourian — upper Carbonic (upper 

 Coal Measure) of central U. S. 



Mold — any impression of an object, 

 either external or internal (see I., 3). 



Molt — to shed the skin, hair, feathers, 

 horns, carapace, or the like ; also 

 spelled moult. 



Moniliform — jointed; resembling a 

 string of beads 



Moniliform siphuncle — see figs. 1263, 

 1346. 



Monmouth beds — middle Cretacic of 

 Atlantic coast. 



Mono — prefix, meaning one. 



Monocyclic — in a single cycle ; applied 

 to those crinoids having no infra- 

 basals below the basals. 



Monomyarian — applied to those pele- 

 cypods in which the anterior adductor 

 muscle is absent or degenerate, as 

 Ostrea. 



Monongahela formation — upper Car- 

 bonic of Pennsylvania, Ohio, etc. 



Monroan — general term for the upper 

 Siluric. 



Montanan — middle Cretacic of the in- 

 terior. 



Monterey formation — Oriskanian of 

 Maryland. 



Monticule — an elevation. In certain 

 Bryozoans and coral colonies these 

 commonly carry the larger apertures. 



Monticuliporoids — compound calcareous 

 bryozoa with the walls of the zoecia 

 thickened in their outer region with 

 numerous cystiphragms (genera 26- 



34). 



Moorefield shales — middle Mississippic 

 of Arkansas. 



Morris coal beds — see Mason Creek 

 beds. 



Morrison formation — upper Jurassic of 

 Front Range region. 



Moscow shale — middle Devonic of New 

 York. 



Mt. Auburn beds — upper division of the 

 Maysville or middle Cincinnati group. 



Mt. Hope beds — division of the Mays- 

 ville or middle Cincinnati group. 



Mt. Laurel formation — middle Cretacic 

 of Atlantic coast. 



Mt. White formation — lower Cambric 

 of Canadian Rockies. 



Mucro — a pointed end. 



Mucronate — produced into a long point- 

 ed extension. 



Multi — prefix, meaning many. 



Multicellular — composed of more than 

 one cell. 



Multilocular — of many locuL-e or cham- 

 bers. 



Multivinculum — in pelecypods, applied 

 to the ligament when consisting of 

 many elastic strands stretched from 



