688 



Sabellitbrmia, 128, 154 



Sabinea, Mysis larva of, 215 



Sacculi, formation of, in Antedon rosacea, 552 



Sagartia parasitica, 85 



Sagitta bipunctata, development of, 428-435 



Salamander, changes induced in by changes 



in environment, 651 

 Salivary glands, formation of, in Callidina 



russeola, 424 ; in Loligo, 358, 364 ; in 



Peripatus capensis, 175 

 Salpa, 637, 639, 640 ; development of, 635, 



636 

 Scaphopoda, 291 ; ancestors of, 368, 369 ; 



development of, 325-329 

 Scarabaeidae, 277 

 Schizocoele, formation of, in Polygordius 



appendiculatus, 150 

 Schizopoda, 177, 185, 192, 202, 210, 213, 



216, 218 

 Scirtopoda, 418 

 Scleroblasts of Gfrantia, 43 

 Scoleciformia, 128, 153 

 Scolopendra, 285 ; development of, 281-284 

 Scorpion, 221 ; development of, 239-241 

 Scorpionidea, 221 



Scutum, formation of, in Cirripedia, 202 

 Scyllarus, 214 



Scyphistoma, 72, 75 ; of Aurelia, 70 

 Scyphozoa, 78, 79, 96, 166, 661 ; develop- 

 ment of, 67-76 



Sea-anemone, definition of, 87 

 Sea-spiders, 242 

 Sea-urchin, eggs of cross - fertilized with 



foreign sperm, 17 

 Second maxilla in Astacus, 186 

 Second maxillary segment in Donacia, 252 

 Second polar body, definition of, 9 

 Second somatoblast in segmenting egg of 



Dreissensia, 335 ; in segmenting of Nereis, 



156 

 Secondary body-cavity, equivalent to coelom, 



165 

 Secondary dorsal organ, formation of, in 



Donacia, 247, 259 

 Secondary germ - cells, formation of, in 



Donacia, 263 

 Secondary gill-slits, formation of, in larva of 



Amphioxus lanceolatus, 604 

 Secondary madreporite, formation of, in 



Synapta digitata, 539 

 Secondary mesenchyme, formation of, in 



Ophiothrix fragilis, 487 

 Secondary mesoderm, formation of, in egg of 



Astacus, 181 

 Secondary radial plates, formation of, in 



Antedon rosacea, 556 

 Secondary stomodaeum, formation of, of 



Callidina russeola, 423 

 Secondary stone - canals, formation of, in 



Antedon rosacea, 557 

 Secondary trochoblasts, formation of, in 



embryo of Crepidula, 321 ; in embryo of 



Fiona, 321 ; in embryo of Patella, 297 : 



in embryo of Phascolosoma, 375 



Secondary yolk pyramids, formation of, in 

 egg of Astacus, 183 



Segmentation-cavity, 165 



Segmentation of coelom of Aster ina gibbosa, 

 472, 473 



Segmentation of the egg, definition of, 27 



Segmentation of the egg of Agelena, 223 ; 

 of Amphioxus lanceolatus, 586, 587, 588 ; 

 of Antedon rosacea, 545 ; of Ascaris 

 megalocephala, 440-443 ; of Astacus, 179, 

 180 ; of Asterias, 460 ; of Aurelia aurita, 

 68 ; of Balanoglossus clavigerus, 570 ; of 

 Beroe, 89-92 ; of Branchipus, 194 ; of 

 Callidina russeola, 419-421 ; of Cere- 

 bratulus lacteus, 119 ; ofCucv.mariaplanci, 

 541 ; of Cynthia partita, 612-614 ; of 

 Dentalium, 326-328 ; of Dolichoglossus 

 pusillus, 583 ; of Donacia and of Dory- 

 phora, 246 ; of Dreissensia, 333-338 ; of 

 Echinus esculentus, 506, 507 ; of Eu- 

 phausia, 192 ; of Geryonidae, 67 ; of 

 Holothuria tubulosa, 541 ; of Julus, 284 ; 

 of Lepas, 195 ; of Macrobiotics, 243 ; of 

 Membranipora, 387 ; of Nephelis, 160 ; 

 of Ophiothrix fragilis, 486 ; of Pallene, 

 243 ; of Paludina, 310 ; of Patella, 292- 

 295 ; of Pedicellina, 398 ; of Peripatus 

 capensis, 170 ; of Phascolosoma, 373-375 ; 

 of Planocera inquilina, 104-109; of 

 Polygordius, 131-139 ; of Polyphemus, 

 193 ; of Pyrosoma, 632 ; of Sagitta 

 bipunctata, 428, 429 ; of Salpa, 635 ; of 

 Scolopendra, 281 ; of the Scorpion, 239 ; of 

 Sepia, 354 ; of Sycandra raphanus, 37, 

 38 ; of Synapta digitata, 530 ; of Tere- 

 bratulina septentrionalis, 408 ; of Tubu- 

 laria mesembryanthemum, 54 ; of Urticina 

 crassicornis, 77 



Segmentation of mesoderm, cause of, in 

 Annelida, 165 



Segments, formation of, in embryo of 

 Agelena, 225 



Sense-tentacle, formation of, in Aurelia. 72 



Sensory-plate of larva of Asterias, 461 



Sepia officinalis, 353, 354, 366 



Septa, formation of, in Caryophyllia cyathus, 

 87 



Septal funnels, formation of, in larva of 

 Aurelia, 70 



Serosa, formation of, in embryo of Donacia, 

 247 ; in embryo of Doryphora, 261 ; in 

 embryo of Lepisma, 265 ; in embryo of 

 Machiles, 265 ; in embryo of the Scorpion, 

 240 



Serpulidae, 416, 520 



Sertularia, development of gonophore bud of, 

 62 



Sex-chromosomes, 13, 15 



Sexual germ, definition of, 2 



Shell, formation of, in Acmaea, 304 ; in 

 Dentalium, 329 ; in Dreissensia, 339 ; in 

 Fissurella, 305 ; in Haliotis, 305 ; in 

 Loligo, 357 ; in Cyphonautes larva of 

 Meiribranipora, 392 ; in Nautilis, 357 ; 



