GLOSSARY. 



839 



Little River group — a continental for- 

 mation regarded by Canadian geolo- 

 gists as upper Devonic, but by paleo- 

 botanists as lower Carbonic (Kana- 

 waha group). 



Littoral — referring to the shores of seas 

 or lakes. Littoral animals are those 

 which inhabit the shallower portions 

 of lakes or seas where light is present. 

 The littoral zone extends from high 

 water to the edge of the continental 

 shelf. . 



Living chamber — the last chamber in 

 the shell of a cephalopod ; the cham- 

 ber occupied by the body of the ani- 

 mal ; body chamber. 



Livingston formation — uppermost Cre- 

 tacic of Montana. 



Lobes — backward bending portions of 

 the suture of cephalopod shells ; they 

 point away from the aperture of the 

 shell (see II., 21, 23). 



Lobulate — with lobes. 



Lockport dolomite — division of the 

 Niagaran of New York. 



Loess — continental Pleistocenic of the 

 Mississippi and Missouri Valley. 



Logan sandstone — upper division of 

 Waverly group. 



Longitudinal — in a direction parallel 

 with the length. 



Lophophore — in Bryozoa and Brachio- 

 poda the curved fleshy ridge sur- 

 rounding the mouth and bearing the 

 hollow tentacles (see I., 174). 



Lorraine shales — upper Ordovicic of 

 New York, etc. 



Louisiana limestone — lower division of 

 the Kinderhook of the Mississippi 

 Valley. 



Louisville limestone — Niagaran of Ken- 

 tucky and Indiana. 



Loup Fork beds — upper Miocenic to 

 Pliocenic of Great Plains region. 



Lowville limestone — upper Chazyan of 

 New York. 



Lucas dolomite — upper Monroan of 

 Michigan, Ohio, etc. 



Ludlowville shale — middle Devonic of 

 New York state. 



Lunarium — in Bryozoa, a more or less 

 thickened portion of the posterior 

 wall which is curved to a shorter 

 radius and often projects above the 

 plane of the zooecium (see Fig. 182, 

 /). 



Lunule — in pelecypods, the depression 

 in front of the beak ; in echinoids, 

 one of the perforations present in the 

 tests of some forms (see Fig. 1926). 



McAlester formation — lower Carbonic 

 of Arkansas and Oklahoma. 



Macerate — to soften and separate by 

 immersion in a liquid. 



Macro — a prefix, meaning great. 



Macrocorallites — the larger corallites in 

 a compound corallum. 



Macula (plural macula) — a flattened or 

 depressed area upon the surface of a 

 bryozoan colony. 



Madera limestone — lower Carbonic of 

 New Mexico, etc. 



Madison limestone — Mississippic of 

 Montana. 



Madison sandstone — upper Cambric of 

 Wisconsin. 



Madreporic — in echinoderms, referring 

 to the madreporite. 



Madreporite — in echinoids, a porous, 

 sieve-like structure located in the 

 apical system ; also the plate contain- 

 ing it — the largest of the five genital 

 plates (see Fig. 1935, ni). Like- 

 wise present in cystoids, asteroids, 

 etc. 



Magdalena group — lower Carbonic of 

 New Mexico, etc. 



Magnesian, lower — basal Ordovicic of 

 the upper Mississippi region. 



Magothy formation — middle Cretacic 

 of Atlantic coast. 



Malone formation — upper Jurassic of 

 Texas. 



Mamelon — a small hemispherical eleva- 

 tion. In echinoids, the rounded knob 

 or ball forming the top of a tubercle 

 upon which rests the spine (see Figs. 

 1913, 1918). 



