43 6 Glossary. 



Littoral. — Inhabiting the seashore. 



Loess. — A marly deposit of recent (Post-Tertiary) date, which occupies a 

 great part of the valley of the Rhine. 



Malacostraca. — The higher division of the Crustacea, including the 

 ordinary Crabs, Lobsters, Shrimps, &c, together with the Woodlice and 

 Sand-hoppers. 



Mammalia. — The highest class of animals, including the ordinary hairy 

 quadrupeds, the Whales, and Man, and characterised by the production 

 of living young which are nourished after birth by milk from the 

 teats (Mammse, Mammary glands) of the mother. A striking difference 

 in embryonic development has led to the division of this class into two 

 great groups ; in one of these, when the embryo has attained a certain 

 stage, a vascular connection, called the placenta, is formed between the 

 embryo and the mother ; in the other this is wanting, and the young 

 are produced in a very incomplete state. The former, including the 



- greater part of the class, are called Placental mammals ; the latter, or 

 Aplacental mammals, include the Marsupials and Monotremes (Orni- 

 thorhynchus). 



Mammiferous. — Having mammse or teats (see Mammalia). 



Mandibles, in Insects. — The first or uppermost pair of jaws, which are 

 generally solid, horny, biting organs. In Birds the term is applied to 

 both jaws with their horny coverings. In Quadrupeds the mandible 

 is properly the lower jaw. 



Marsupials. — An order of Mammalia in which the young are born in a 

 very incomplete state of development, and carried by the mother, while 

 sucking, in a ventral pouch (marsupium), such as the Kangaroos, 

 Opossums, &c. (see Mammalia). 



Maxilla, in Insects. — The second or lower pair of jaws, which are com- 

 posed of several joints and furnished with peculiar jointed appendages 

 called palpi, or feelers. 



Melanism. — The opposite of albinism ; an undue development of colouring 

 material in the skin and its appendages. 



Metamorphic Rocks. — Sedimentary rocks which have undergone altera- 

 tion, generally by the action of heat, subsequently to their deposition 

 aud consolidation. 



Mollusca.— One of the great divisions of the Animal Kingdom, including 

 those animals which have a soft body, usually furnished with a shell, 

 and in which the nervous ganglia, or centres, present no definite general 

 arrangement. They are generally known under the denomination of 

 " shell-fish ;" the cuttle-fish, and the common snails, whelks, oysters, 

 mussels, and cockles, may serve as examples of them. 



Monocotyledons, or Monocotvledonous plants.— Plants in which the 

 seed sends up only a single seed-leaf (or cotyledon) ; characterised by 

 the absence of consecutive layers of wood in the stem (endogenous 

 growth), by the veins of the leaves being generally straight, and by the 

 parts of the flowers being generally in multiples of three. {Examples, 

 Grasses, Lilies, Orchids, Palms, &c.) 



Moraines. — The accumulations of fragments of rock brought down by 

 glaciers. 



Morphology. — The law of form or structure independent of function. 



