690 



INVERTEBRATA 



Strepsiteue thread, definition of, 4 

 Strobila of Aurelia, 72 

 Stabilization, 75 ; definition of, 72 

 Strongylocentrotus, 511, 630; egg of, 3; 



entelechy of, 21 



Strongylocentrotus droebachiensis, 505 

 Strongylocentrotus franciscanus, 505 

 Strongylocentrotus lividus, 504, 506 

 Strongylocentrotus purpuratus, 505 

 Sub-genital pit, formation of, in Aurelia, 



71 

 Sub - intestinal ganglion, formation of, in 



Paludina, 315 

 Sub-neural gland, formation of, in Ciona 



intestinaiis, 625 ; in blastozooid of Uro- 



chorda, 639 

 Sub-neural sinus, formation of, in Peripatus 



capensis, 1/4 

 Snb-oesophageal ganglion, formation of, in 



Agelena, 232, 235 ; in the Scorpion, 241 ; 



in Terebratulina septentrionalis, 412 

 Sub-stomachal canals, formation of, of Beriie ' 



94 

 Sub-tentacular canals, formation of, in Beroe, 



94 

 Sucker (internal sac), formation of, in Cypho- 



nautes larva, 392 



Sucker muscles of Cyphonautes larva, 393 

 Sucker of Cyphonautes larva, 401, 406 ; 



eversion of, 394 

 Sucking tube, formation of, in Achtheres am- 



bloplitis, 207 

 Supporting lamella of Urticina crassicornis, 



79 

 Supra-intestinal ganglion, formation of, in 



Paludina, 315 

 Supra-oesophageal ganglion, formation of, 



in Sagitta bipunctata, 432 ; in Tere- 

 bratulina septentrionalis, 411 

 Sycandra raphanus, later development of, 



43 ; segmentation of the egg of, 35 

 Syconidae, 37 

 Symmetrical post-larval stage of Anomura, 



216 



Symphyla,.280, 281 

 Synapta, 547, 565 



Synapta digitata, development of, 529-541 

 Synapta vivipara, 529 ; development of, 



539-541 

 Syncarida, 177 

 Syndesis, definition of, 4 

 Synizesis, definition of, 4 



Tactile organ of Sagitta bipunctata, 433 

 Tadpole of Ascidians (Tuuicata), 654 ; of 



simple Ascidian, 619-622 

 Tadpoles, determination of sex of, 17 

 Taemolae of larva of Aurelia, 69 ; of Beroe, 



94 ; of medusa of Tubularia, 58 

 Tail, formation of, in larva of Amphioxus 



lanceolatus, 596 ; in Callidina russeola, 



423 ; in embryo of Cynthia partita, 618 ; 



of Spermatozoon, definition of, 7 ; of larva 



of Tunicata (Urochorda), 608 



Tail-bud, formation of, in larva of Amphioxus 

 lanceolatns, 596 



Tail-endoderm, origin of, of larva of Cynthia 

 partita, 614 



Tardigrada, 169 ; development of, 243 



Teeth, formation of, in Echinus esculentus, 

 515 



Teleostei, 22 



Telescoped development, definition of, 153 



Teloblast of Criodrilus lacuum, 158 ; of 

 Ne2)helis, 161 ; of Polygordius, 144 



Telolecithal egg, definition of, 26 ; of Cepha- 

 lopoda, 354 ; of Scorpion, 239 ; of Peri- 

 patus, 177 



Telotroch of Toruaria larva of Balanoglossus 

 davigerus, 574 ; formation of, of larva of 

 Dreissensia, 337 ; in larva of Patella, 299 ; 

 in Actinotrocha larva of Phoronis, 381 ; 

 in larva of Polygordius, 140, 144 



Telotrochal larva, definition of, 153 



Telson, formation of, in Astacus, 189 



Tendon-cells, metamorphosis of, in larva of 

 Galerucella ulmi, 208 



Tentacle pockets, formation of, in Callianira, 

 95 



Tentacle-sheath of Bugula, development of, 

 in bud, 397 



Tentacles, formation of, in Antedon rosacea, 

 550, 551 ; in Callianira. 95 ; in Paludina, 

 315 ; in Pedicellina echinata, 403 ; in 

 Pliascolosoma, 379 ; in Actinotrocha larva 

 ofPhoronis, 381 ; in adult Phoronis, 383 ; 

 in Polygordius appendicvlatus, 148 ; in 

 medusa of Tubularia, 58 



Terebellidae, 157 



Terebelliformia, 128, 153 



Terebratulina septentrionalis, development 

 of, 407-413 



Teredo, 348 



Tergum, formation of, in Cirripedia, 202 ; 

 in Limulus, 238 ; in Scolopendra, 283 



Terminal plates, formation of, in Amphiura 

 squainata, 499 ; in Asterina gibbosa, 478 ; 

 in Echinus esculentus, 517 



Terminal threads of ovaries, formation of, in 

 Phyllodromia, 263 



Tertiary radial plates, formation of, in Ante- 

 don rosacea, 556 



Test, formation of, in simple Ascidian, 622 



Test-cells in larva of simple Ascidian, 622 



"Test-cells " (follicle cells), in egg of Cynthia, 

 partita, 610; of Pyrosoma, 632; of Salpa, 

 635 



Testicardines, 406, 407 



Testis of Ascaris megalocephala, 438 ; forma- 

 tion of, of Molgula, 628 



Tetrads, definition of, 12 



T-giants, development of, of Ascaris megalo- 

 cephala, 448, 449 



Thalassinidae, 215 



Thaliaceae, 568, 608, 635, 636, 637 



Thaumatocrinus, 560 



Theca, formation of, in Caryophyllia cyathus, 

 87 



