630 



INDEX 



Mesenteron {cont.) 



Hirudinea, 263; of Insecta, 388; 

 of Nematoda, 218 



Mesoblast, see Mesoderm 



Mesoblastic somites, see Mesoderm 

 segments 



Mesocerebrum, see Deutocerebrum 



Mesoderm, 120; 121, 122, 123; in 

 the trochosphere, 251; of Arach- 

 nida, 448 ; of Arthropoda, 280 ; of 

 Chordata, 584, 597. See also 

 Mesenchyme, Mesoderm seg- 

 ments (Mesoblastic somites), Me- 

 sothelium 



Mesoderm segments (Mesoblastic 

 somites), 280; of Arachnida, 444, 

 448; of Arthropoda, 279, 280; of 

 Chaetopoda, 229, 251; of Chor- 

 data, 584; of Onychophora, 283 



Mesogloea, see Structureless lamella 



Mesosoma, 271, 449, 452 



Mesostoma, 186; 177, 178 



M. ehrenbergi, 189 



M. quadrangular e, 189 



Mesothelium, 121 ; 122. See also 

 Mesoderm segments (Mesoblastic 

 somites) 



Metabasipodite, see Preischiopodite 



Metabola, see Pterygota 



Metaboly, 14, 46, 47 



Metacerebrum, see Tritocerebrum 



Metacestode stage, 202, 204 



Metachronai rhythm, 13 ; 172 



Metameric segmentation, 251 



Metamorphosis, see Life history 



Metanemertini, 208 ; 205 



Metapneustic, 439 



Metasoma, 271, 449, 452 



Metasome, 333 



Metasternite, 450 



Metastoma, of Crustacea, 303 ; of 

 Eurypterida, 453 ; of Trilobita, 287 



Metazoa, 3; i, 4, 19, 23, 30, 39, 

 117 



Metepipodites, 300; 299. See also 

 Branchia 



Metridiuni, 170 



Miastor, 396 



Microchromosomes, 22 



Microfilaria diurna, 223 



M. nocturna, 223 



Microgametes, see Male gametes 



Microhydra, 143; 142 



Micromeres, 248 



Micronephridia, 256 



Micronuclei, 21 ; 22, 28, 29, 30 



Micropteryx, 429 



Microspheric form, 70 



Microsporidia, 95 



Microstoma linear e, 188; 189, 199 



Mid gut, see Mesenteron 



Mid-gut caeca, see Mesenteric caeca 



Milk glands of tsetse fly, 394 " 



Millepora, 144 



Mitoses of Protozoa, 19 



Molar process, 348 



Mollusca, 470; 1,2; Types of, 471 



Molpadida, 577 



Monas, 56; 12, 37, 41 



M. vulgaris, 57 



Mono cyclical rotifers, 213 



Monocystis, 92; 8, 27, 32, 33, 91, 92 



M. lumbrici, 92 



M. magna, 92 



Monograptus, 148; 149, 150 



M. colonus, 149 



Monopylaea, 71 



Monosiga, 60 



M. brevipes, 59 



Monothalamia, 68 ; 67 



Monotocardia, 489; 478, 491 



Monstrilla, 335 



Montipora, 169 



Mosaic disease, 417 



Mosaic vision, 278 



Motile organs of Protozoa, 1 1 



Moulting, 274, 334, 398 



Mouth, of Arthropoda, 271; of 

 ascidian tadpole, 597, 598; of 

 Balanoglossus, 585 ; of Brachio- 

 poda, 539; of Chilopoda, 377; of 

 Coelenterata*, 129, 130, 131, 140, 

 143, 145, 151, 152, 156, 159, 168, 

 170, 171, 172; of Echinodermata*, 

 546, 555, 564, 571, 578; oi Helix, 

 482 ; of Hirudinea, 263 ; of Hyda- 

 tina, 211; of Insecta, 383; of 

 Lepas, 339; oi Peripatus, 283; of 

 Platyhelminthes*=, 174, 181, 189, 

 190; of Protozoa*, 15, 97, 100; of 

 Trilobita, 287 ; of Triploblastica, 

 121. See also Alimentary canal. 

 Branchial opening, Mouth parts 



Mouth parts (limb-jaws and lips), of 

 Arthropoda, 270, 271, 272-3; of 

 Crustacea*, 292-3, 302, 303, 318, 

 325, 331, 333, 334, 335, 339, 348, 

 355, 356, 358, 359, 368, 369; of 



