INDEX 



663 



Sigma (a slender rod-like spicule curved in 

 the shape of the letter C), 220, 222 ■ 



Sigmaspire (a sle7ider rod -like spicule 

 twisted through .about a single revolu- 

 tion of a spiral, and consequently having 

 the form of a C or an S according to the 

 direction in which it is viewed), 222 



Siliceous plates, of test of Rhizopods, 29, 

 53 f. 



Siliceous skeleton of Holiozoa, 71, 74 ; of 

 Radiolaria, 76 f. ; of SilicoHagellata, 110; 

 of Sponges, 171 f., 175f., 195 f. 



Silicified cell-wall of some Dinoflagellates, 

 130 



Silicispongiae, 195, 197 



Silicofiagellata, 86, 110, 114 



Silkworm infested by disease pcbrine, due 

 to Xosema homhycis, 107 



Simpson, on life-cycle of Ciliatix, 148 n. 



Siphon, of Ecliinns esculentus, 516 ; of 

 Echinarachnius parma, 546, 547 



Siphonia, 215 



Siphonoglyph, 334, 334, 369, 410 



Si2)Jwnogorgia, 349 



Siphonogorgiidae, S49 



Siphonophora, ~97 f. ; dactylozooids, 299 ; 

 food, 304 ; gastrozooids, 299 ; gono- 

 zooids, 302 ; hydrophyllia, 300 ; life- 

 history, 302 ; nectocalyces, 298 ; pneu- 

 matophore, 300, 307 f. ; stolon, 301 



Siphonozooids, 332 ; of Peunatulacea, 359 



Sipunculidae, 576 



■Sipnnmhis, 563 



Skeleton, intermediate or supplemental 

 of Perforate Foraminifera, 59, 63, 66 ; 

 of Heliozoa, 71, 74; of RaphuHipIirys, 

 74 ; of Radiolaria, 76 f., 77 f., 81 f., 84 ; 

 of Spumellaria, 77, 77, 83 ; of Adi- 

 nomma asteracanthion, 77 ; of Acan- 

 tharia, 76 i., 78, 80, 82 ; of JLtphacantha, 

 78 ; of Doratasjjis, 80 ; of Nassellaria, 

 76, 78, 82, 83 ; of Lithocercus annu- 

 laris, 82 ; of Theuconus, 80 ; of Phaeo- 

 daria, 76, 79, 82, 84, 85 ; of Avlac- 

 tiniuvi actinastrum, 82 ; of C.'hallen- 

 geridae, 85 ; of Pharyngella, 85 ; of 

 Haeckeliana, 85 ; of Tuscaroru, 85 ; of 

 Diatomaceae, 84 ; gelatinous, of y'olrox, 

 126— see also Shell, Test, Theca— of 

 Asterias ruhcns, 434 f. ; of disc of 

 Ophiuroidea, 493 ; internal, of E-^'ina- 

 rachnius parma, 545, 548 ; of C -jea- 

 stroidea, 548 ; of Larjanum, 54b ; of 

 Clypeasler, 548 ; of Echinocyainvs, 548 ; 

 of Echinanthidae, 549 ; of Laganidae, 

 549 ; of Ifolothuria nigra, 560 ; of 

 Holothur ' ea, 569 ; of Aspidochirota, 

 569 ; of Uendrochirota, 569 ; of Elasi- 

 poda, 569 ; of Molpadiida, 569 ; of 

 Svnaptida, 569 ; of calyx and arm in 

 Crinoidea, 588 



Sladen, on classification of Asteroidea, 460 



Sleeping-sickness, 120 



Snow, red, 125 



Solttster, 453, 455, 463 ; fossil, 475 ; .S'. 

 endcca, 463 ; >i. papposns, 463 



Solasteridae, 453, 455, 458, 462, 460 



Solenocaiihm, 3o0 



Sollas, I. 15. J., on Sponges, 163 f. 



Sollas, W. J., on Sponges, 165 n., 168, 

 172 n., 176 n., 183 n., 207 n., 208, 

 212 n., 215 n., 216, 219 n., 233 n., 

 234 n., 238 n. ; on Palaeodiscus, bbl 



Solniaridae, 296 



Snlinaris, 296, 297 



Soluble substances in greater or less con- 

 centration, effect on protoplasm, 7 f. , 

 22 f. 



Sore, Oriental, 121 



Spallanzani, on origin of organisms of 

 putrefaction, 43 



Spanioplon, 223 



Sparshall's discovery oi Noctiluca, 135 



Spatangidae, 554, 559 



Spatangoidea, 529, 549 t, 556, 559, 561, 

 577 



Spatangus, 553, 555 ; S. jjurpurens, 555 ; 

 S. raschi, 555 



Specialisation in Metazoa and Volvox com- 

 pared, 129 f. 



Specific gravity of living protoplasm, ] 3 n. 



Spencer, Herbert, on limit of growtli, 23 



Spencer, W. B., on Hydroids, 271 n., 279 



Spencerian. fission at limit of growtli, 23 ; 

 rhythm, 30 f. 



Sperm, Spermatozoon, 17, 31, 33 f. ; = 

 spermogametes, 33 ; penetration of 

 ovum by, 34 ; rheotaxy of, in Mammals 

 and Sauro]isiila, 34 ; of Sporozoa, 18 ; 

 of Pterorrphahis, 99, 108 n. ; of Stylo- 

 rhynchus, 99, 100 ; of Coccidiiim, 100, 

 101 f. ; of Acystosporidae, 104 f. ; of 

 Sarcocystis tcnclla, 108 n. ; of bisexual 

 Protozoa and most Metazoa comparable 

 with Flagellata, 109 ; of Volvox globator, 

 127 f. ; of Evdorina, 129 



S])ermatogone (=a brood -mother -cell, 

 whose oli'spring are sperms) of Cocci- 

 diaceae, 100 f.; of Volvox globator, 127f. ; 

 of Kinlorina, 129; of Acystosporidae, 

 104 f. 



Spermatozoon, 17, 18 — see also Sperm 



Sperosoma, 536 



Spliaeractinia, 2S3 



Sphaerechinus, 530, 540, 541 ; .S'. granu- 

 lar is, 541 



Sji/iaerella, 111 ; S. lacustris, 126 : >'. 

 nivalis, 125 ; S. jiluvialis, 125 f.. 126 



Sphaerellaria, 77, 77 ; geological occurrence 

 of, 88 



Sphaeridium, oi Strongylocenlrotns, 523 ; of 

 Echinus esculeutns, 524 ; of Ecliin- 

 arar.hnius parma, 545 ; of Echino- 

 cardium cordatum, 551 



