INDEX 



683 



Nerve-cord, formation of, in Phascolosoma,B77 



Nerve-ring; formation of, in adult Ant<:<l<>n 

 rosacea, 554 ; in Cuci'mi/i-ia /i/n/icf, 542 



Nervous system, formation of, in A g<-/, ,/n, 

 226; in embryo (and larva) of Antedon 

 rosacea, 547; in Astoms, 184; in adult 

 Asterinagibbosa, 477; in larva of 1)1 ///'///, 

 637 ; in ])iuiclii, 257, 258 ; iu larva of 

 Ec/iiit/txi'xni/eiifiiK, 516 ; in adult Ech inns 

 esculentvs, 574 ; in Ascidiozooid of /'///"- 

 soma, 640 ; in C'yathozooid of Pyrosoma, 

 634 ; in Salpa, 635 ; in X<-<i/<->ji<'n,/,;i. 282 ; 

 in larva of Si/iiapta digitata, 536 ; in 

 blastozooid of Urochorda, 638 



Neural folds in embryo of Ami>]ii.i-us 

 lanceolatus, 591 ; in Tornaria larva of 

 Balanoglossus, 578 ; in embryo of <'//ntIn' 

 partita, 619 



Neural groove, formation of, in Donacia, 258 



Neural plate, formation of, iu embryo of 

 Amphioxus h/ncenlntug, 541 ; iu Tornaria 

 larva of l>iilan<>al<isss>ix, 578 ; in embryo 

 of Cynthia partita, 614 



Neural tube, formation of, in embryo of 

 Amphio.cns lanceolatus, 593 ; in Toriiaria 

 larva of Balanoglossus, 578 ; in eniliryo 

 of Cynthia partita, 619 ; in embryo of 

 Salpa, 636 



Neurenteric canal, formation of, in embryo 

 of .1 mphioxus lanceolatus, 592 ; in embryo 

 of Cynthia partita, 619 



Neuroblasts ofD<Ktci<i, 258 ; of ^\' '/>]i< 7 is, 161 



Neuropore, formation of, in embryo of 

 Cynthia partita, 619 ; in larva of Am/i///- 

 otiix Imici-olatus, 593 ; in larva of Jiis- 

 tajilia, 632 



Nitscliia, 506 ; cultures of, 131 



Notochord, formation of, supposed in Actino- 

 trocha larva, 381, 383 ; in J mpli /<<.<(/*, 592; 

 iu larva of C'l/iithin jiarfifa, 614; in New 

 England Tornaria, 579 



Nuclear sap, definition of, 3 



Nucleolus, definition of, 3 



Nucleus of unripe ovum, 3 



Nucula, 349 



Nymphs of Hemimetabola, 287, 288 



Oceania, 59 ; medusae of, 59 

 Ocelli of Dytiscus, 273, 274, 275 

 Octant of egg of Bertie, definition of, 91 

 Ocular plates of Kchinvs ewnli'nt nx, 577 

 Odonata, 245, 272, 277, 286 ; embryonic 



development of, 266 



Oesophagus, formation of, in Agelena, 235 ; 

 in Antedon r<n<acf, 550; in Astficiis, 

 183 ; in larva of Asterias, 462; in larva 

 of Balanogloss/us clavigerus, 573 ; in larva 

 of Ophiotlu-i.i- f rag His, 4*7 ; in larva of 

 Synapta dif/itnln. 532 ; in T<'i-cln-ati<l!ii(i 

 septentrionalis, 411 



Olfactory organ of Sni/iffn bipunctata, for- 

 mation of, 434 



Oligochaeta, 128, 600 ; development of, 

 156-159 



Ommatidium, formation of, in compound eye 



of Axtneitx. 189 ; in compound cyt- of 



l>iilisi-iia, 276 ; in lateral eyes of Limi'/nfi. 



237 



Onychophora, 169, 206, 285; development 



of, 170-176 



Oocyte of first order, 9 ; definition of. .", 

 Oocyte of second ordei-, 9 

 Oogenesis, definition of, 2 

 Oogonium, definition of, 3 

 Oostegites of Entoniscidae, '219 

 Oozooid of Botryllidae, 642 ; of Salpa, 640 

 Open larva of Patella, formation of, 307 

 Operculum of Patella, formation of, 303 

 Ophiopluteus larva, 498, 508, 509, 521, 

 529, 532, 533, 565, 654 ; compared with 

 Bipinnaria larva, 491, 492 ; compared with 

 Echinopluteiis larva, 51 1 ; definition of, 490 

 Ophi<>thri.,-j'r<i</ilix, 484, 501, 503, 504, 507, 

 508, 514, 529; abnormal development of, 

 502 ; development of, 485-498 

 <>jili //'/, larva of, 489 

 Ojihiura brereispina, 484 ; development of, 



501-503 



Ophiuroidea, 287, 461, 464, 456, 508, 

 514, 515, 522, 523, 530, 531, 534. 536, 

 538, 541, 542, 543, 560, 564, 565 ; de- 

 velopment of, 484-504 



Opisthobranchiata, 280, 281, 291, 320, 321 

 Optic ganglion, formation of, in An/nfus, 184 

 Oral coelom, formation of, in Ant<'<li< 



i-iixacea, 552 



Oral cone of .1 iirHia, 69 

 Oral lobe of larva of Echinus esculenius, 509 

 Oral ring of plates, formation of, in larva of 



Antedon rosacea, 547 



Oral tentacles of T'wftw&m'a, development of, 56 

 Organ-forming substances, 658, 659 ; in egg 

 of Cynthia, 631 ; in egg of Dentalium, 

 330-332 ; in egg of Paludina, 309 

 Orgauogeny, definition of, 27 

 Orientation, methods of, 34 

 Orthoptera, 201, 245, 272, 277, 278, 286, - 

 Om-m-ella, 43, 44, 51 ; inet!imoriilivi> of, 1 I 

 Osmic acid (Osmium tetroxide), definition of, 



32 ; use of, 32 



Ostium, formation of, in larva of Ani-i-/in, 71 

 Ostium of heart, development of, in Ai/c/cn'i. 



229 



Ostracoda, 177, 185 ; ancestral origin of, 212 

 n*i ,-i-a., brephic stage of, 22 

 n^hra Virginia no, veliger larva of, 348 

 Otocysts, formation of, in 1>> iiliilium. '!'_".' : 

 in Jtri'ixx'-i/xi'i. 342 ; in /.n/i;/". -'''^ : in 

 Paludina, 315; in Patella, 301; in 

 Xi/nii/iiii il'ujiliiin, 539 



Ovary of Ascaris megalocephala, i:;> : 

 developmenl of, in .lulim. 2si . ot 

 Miililiiln, 62S : of Phyllodromia, -<>'' 

 Oviduct, formation of, in Ascaris megalo- 

 cephala, 138 : in Molgula, 628, f,2 ( .i : in 

 Phyllodromia, 2ii3 ; inSagittabipimctata, 

 i:. i 



( (viini (a) definition of, 11 



