INDEX 



691 



Thecidium mediterranenm, 407 



Thecoida, 456 



Thoracic region of embryo of Donacia, 251 



Thoracico-abdorninal rudiment in embryo of 

 Astacus, 180 



Thysanura, 245, 287, 288 



Tiara, medusa of, 59 



Tip-cells of Molluscan cross in embryo of 

 Crepidula and Fiona, 321, 322; in em- 

 bryo of Patella, 294, 297 



Tipulidae, 278 



Tongue - bars, formation of, in Amphioxus 

 lanceolatus, 604 ; in New England Tor- 

 uaria, 579 



Tornaria, 1, 569, 582, 585, 605, 606; of 

 Ralanoglossus clavigerus, 574 ; develop- 

 ment of, of Nassau, 579-581 ; New Bug- 

 land, 574-579; of Pacific Coast, 581, 

 582 ; interpretation of, 661 



Torsion of larva of A cmaea, 304 ; of embryo 

 of Paludina, 315, 316 ; of larva of Patella. 

 300 



Tracheae, formation of, in Agelena, 231 ; in 

 Donacia, 258 ; in wings of Doryphora, 273; 

 in Peripatus capensis, 175 



Tracheoles in wings of Doryphora, 273 



Trachymedusae, 53 ; development of, 67 



Transverse ciliated rings, formation of, in 

 larva of Antedon rosacea, 546 ; in larva of 

 Oucumaria planci, 542 ; in larva of 

 Synapta digitata, 536, 537 



Transverse commissures, formation of, in 

 nervous system of Astacus, 185 



Trematoda, 102, 103 



Triaxouia, 37 



Triclada, 102, 103 



Trilobita, 169, 205, 238, 244, 285, 286 



Trilobite larva of Limulus, 238 



Tritocerebrum of Astacus, 184 ; of Donacia, 

 258 ; of Scolopendra, 283 



Trochal disc, formation of, in Cattidina rus- 

 seola, 424 



Trochophore larva, 390, 405, 406, 408, 411, 

 415. 416, 427, 561, 655, 661 ; interpreta- 

 tion of, 164 ; of Acmaea, 320 ; of Annelida, 

 description of, 130, 368 ; of Annelida, 

 compared to Nauplius, 204 ; of Dentalium, 

 328 ; of Dondersia, 325 ; of Dreissensia, 

 337, 338, 368 ; of Eupomatus, 154 ; of 

 Fissurella, 320 ; of Haliotis, 320 ; of 

 Paludina, 310 ; of Patella, 298, 368 ; 

 of Phascolosoma, 370 ; of Polyyordius, 

 139 ; of Polyplaeophora, 320 ; of Sipuncu- 

 loida, 163, 372 ; of Trochus, 320 



Trochus, 320, 322, 323 



Trophi, formation of, in Callidina ru-sseola, 

 424 



Trophocyte of bud of Ephydatia, 48 



Trophozooids of Doiiolum, 640 



Trunk blastema, formation of, in the embryo 

 of Nephelis, 162 ; in the embryo of 

 Phascolosoma, 375 ; in the larva of Poly- 

 gordius, 142 



Trunk-coelom, formation of, in Amphioxus 



lanceolatus, 592 ; in Balanoglossus clavi- 

 gems. 574 ; in Actinotrocha larva of Phor- 

 onis, 381 ; in New England Tornaria, 575 



Tubal cells of archinephridia in Polygordius, 

 140 



Tube-feet, formation of, in Asterias, 471 ; in 

 Asterina gibbosa, 476 ; in Oucumaria 

 planci, 542 ; in Echinus esculentus, 514, 

 517 ; in Ophiothrix fragilis, 493, 495 



Tubularia, 60, 61, 62, 383 ; development of, 

 54-69 



Tubularia indivisa, 54 



Tubularia ?nesembryanthemum, 54 



Tunicata, 406, 413, 564, 568, 659, 662, 

 development of, 608-646 



Turbellaria, 102 



Turret cells in segmenting eggs of Gastro- 

 poda, 322 



Umbrella, 324 



Umbrella cavity, vestigial character of, in 



gonophore of Clava, 62 ; in gonophore of 



Sertularia, 62 ; formation of, in medusa 



of Tubularia, 57 

 Under-basal plates, formation of, in Amphi- 



ura squamata, 499 ; in Antedon rosacea, 



548 ; union of, in Antedon rosacea, 558 

 Underlip, formation of, in Callidina russeola, 



423 



Unio, embryonic development of, 351 

 Unionidae, 349, 350, 351, 353, 655 

 Upper sclerotomes, formation of, in larva of 



Amphioxus lanceolatus, 599 

 Ureter, formation of, in Astacus, 188 ; in 



Dreissensia, 344 ; in Paludina, 314 

 Urnatella, 398 

 Urochorda, see Tunicata 

 Urodela, 656, 657 

 Urticina crassicornis, 85 ; development of, 



76-83 

 Uterus of Ascaris megalocephala, 438 



Vagina in Ascaris megalocephala, 438 ; forma- 

 tion of, in Pedicellina echinata, 401 



Valeriauic acid, iise of, 18 



Valve of intestine, formation of, in larva of 

 Polygordius, 143 



Vas deferens in Ascaris megalocephala, 438 ; 

 formation of, in Molgula, 628 ; in Sagitta 

 blpunctata, 434 



Vegetative pole of the egg denned, 26 



Velella, 64 



Veliger larva, 416 ; of Dentalium, 329 ; of 

 Dreissensia, 338 ; of Gastropoda, 369 ; of 

 Paludina, 310 ; of Patella, 300 ; of Pele- 

 cypoda, 369 ; of Scaphopoda, 369 



Velum, formation of, in larva of Crepidula, 

 321 ; in larva of Dentalium, 329 ; in larva 

 of Dreissensia, 338 ; in larva of Fiona, 

 321 ; in larva of Patella, 300 ; in larva 

 of Protobranchiata, 349 ; in medusa of 

 Tubularia, 58 



Vena cava, formation of, in Loligo, 362 



Ventral blood-vessel, formation of, in Echinus 

 esculentus, 518 



