INDEX 



66 3 



Sigma (a slender rod-like spicule curved in 

 the shape of the letter C), 220, 222 



Sigmaspire (a slender 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 Heliozoa, 71, 74 ; of 

 Radiolaria, 76 f. ; of Silicoflagellata, 110; 

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



Silicified cell- wall of some Dinoflagellates, 

 130 



Silicispongiae, 195, 197 



Silicoflagellata, 86, 110, 114 



Silkworm infested by disease pebrine, due 

 to Nosema bombycis, 107 



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



Siphon, of Echinus esculentus, 516 ; of 

 Echinarachnius parma, 546, 547 



Siphonia, 215 



Siphonoglyph, 334, 334, 369, 410 



Siphonogorgia, 349 



Siphonogorgiidae, 349 



Siphonophora, 297 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 Pennatulacea, 359 



Sipunculidae, 576 



Sipunculus, 563 



Skeleton, intermediate or supplemental 

 of Perforate Foraminifera, 59, 63, 66 ; 

 of Heliozoa, 71, 74 ; of Raphidiophrys, 

 74 ; of Radiolaria, 76 f., 77 f., 81 1, 84 ; 

 of Spumellaria, 77, 77, 83 ; of Acti- 

 nommu aster acanthion, 77 ; of Acan- 

 tharia, 76 f., 78, 80, 82 ; of Xiphacantha, 

 78 ; of Dorataspis, 80 ; of Nassellaria, 

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

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

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

 tinium actinastrum, 82 ; of Challen- 

 geridae, 85 ; of Pharyngella, 85 ; of 

 Haeckeliana, 85 ; of Tuscarora, 85 ; of 

 Diatomaceae, 84 ; gelatinous, of Volvox, 

 126 see also Shell, Test, Theca of 

 Asterias rubens, 434 f. ; of disc of 

 Ophiuroidea, 493; internal, of Er\ina- 

 rachnius parma, 545, 548 ; of C -\iea- 

 stroidea, 548 ; of Laganuvi, 54bf ; of 

 Clypeaster, 548 ; of Echinocyamus, 54 8 ; 

 of Echinanthidae, 549 ; of Laganidae, 

 549 ; of Holothuria nigra, 560 ; of 

 Holothur ' ea, 569 ; of Aspidochirota, 

 569 ; of Dendrochirota, 569 ; of Elasi- 

 poda, 569; of Molpadiida, 569; of 

 Synaptida, 569 ; of calyx and arm in 

 Crinoidea, 588 



Sladen, on classification of Asteroidea, 460 



475 ; 8. 



168, 

 208, 



Sleeping-sickness, 120 



Snow, red, 125 



Solaster, 453, 455, jfBS; fossil 

 endeca, 463 ; 8. papposus, 463 



Solasteridae, 453, 455, 458, /,> 



Solenocaulon, 350 



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



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

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

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

 234 n., 238 n. ; on Palaeodiscus, 557 



Solmaridae, 296 



Solmaris, 290, 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 of Nocliluca, 135 



Spatangidae, 554, 559 



Spatangoidea, 529, 549 f., 556,559, 561, 

 577 



Spatangus, 553, 555 ; 8. purpureas, 555 ; 

 S. raschi, 555 



Specialisation in Metazoa and Volvox com- 

 pared, 129 f. 



Specific gravity of living protoplasm, 13 n. 



Spencer, Herbert, on limit of growth, 23 



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



Spencerian, fission at limit of growth, 23 ; 

 rhythm, 30 f. 



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

 spermogametes, 33 ; penetration of 

 ovum by, 34 ; rheotaxy of, in Mammals 

 and Sauropsida, 34 ; of Sporozoa, 18 ; 

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

 rhynchus, 99, 100 ; of Coccldium, 100, 

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

 Sarcocystis tenella, 108 n. ; of bisexual 

 Protozoa and most Metazoa comparable 

 with Flagellata, 109 ; of Volvox globator, 

 127 f. ; of Evdoriua, 129 



Spermatogone ( = a brood -mother -cell, 

 whose offspring are sperms) of Cocci- 

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

 of Eudorina, 129; of Acystosporidae, 

 104 f. 



Spermatozoon, 17, 18 see also Sperm 



Sperosoma, 636 



Sphaenustimct, 983 



Spkaerechinus, 539, 540, 541 ; S. granu- 

 lans, 541 



Sphaerella, 111 ; S. lacustris, 126 : & 

 nl rails, 125 ; 8. pluvialis, 125 f., 126 



Sphaerellaria, 77, 77 ; geological occurrence 

 of, 88 



Sphaeridium, of Strongylocentrotus, 5: 

 Echinus eseulentus, 524 ; of / 

 arachnius parma, 545 ; of / 

 card I a in cordaiw 



