590 



IXDEX OF SUBJECTS. 



Selachians, teeth in, 259 



Semnopithecus, teeth, 204 



Sepidium tuberculatum, double (?) an- 

 tenna, 551 



Sex, analogy with Discontinuous Varia- 

 tion, 66 



Sexual characters, statistics as to, in 

 Beetles, 38; Earwigs, 40 

 of Hepialus in Shetland, 254 

 of Phalanger in Waigiu, 254 



Sheep, cervical auricles, 180; incisors, 

 245 ; change in form of canines, 245 ; 

 molar, 246; extra horns, 285; poly- 

 dactylism, 373, 380 



Sheep-dog, teeth, 221 



Shetland, variety of Hepialus in, 254 



Shrew, naked variety, 56 



Siamese Twins, 560 



Siberia, Crustacea of salt lakes, 97, 100 



Silis rvficollis, extra"legs, 498 



Silky fowls, 56 



Silpha nigrita, extra legs, 501 ; granu- 

 lata, double (?) leg, 548 



Silurus, extra fin, 540 



Simia, vertebrae, 118; teeth, 200; extra 

 digit, 349 ; extra mamma, 188 



Simultaneity of Variation, possibilities 

 of, 25, 26, 308 ; in fore and hind 

 wings of Lepidoptera, 293; in counter- 

 parts, 569; in colours of segments of 

 Lepidopterous larvae, 303 ; in Chiton 

 idffi, 307; in limbs, 402; in homo- 

 logous twins, 559 ; in radial segments, 

 423; not clearly distinguishable from 

 Symmetry, 569 



Sinistral varieties, 54 



Situs transversus, 465, 560 



Sledge-dog, absence of first premolar, 

 215; division of premolar, 214 



Smerinthus, colours of larvae, ocellatus, 

 pojnili, tilice, 306, 307 



Snakes, vertebrae, 103, 123; axial du- 

 plicity, 561 



Solea, pigmentation of blind side, 471 



Solenophorus strepens, double (?) an- 

 tenna, 551 



Sore.r, naked variety, 56 



Spaniel, teeth, 221 



Species, the problem of, 2. Methods of 

 attacking, 6 

 Discontinuity of, a fact, 2 



Specific Differences, indefinite, 2 



Spermathecae of Earthworms, variation 

 in number, &c. of, 160, 165 



Spharocrinus, imperfect variation to 6- 

 rayed state, 437 



Sphingida?, repetition of markings in 

 larvae of, 26 ; variation in, 304 



Sphinx Ugustri, division of proboscis, 456 



Spinal nerves, 129; Birds, 130; Man, 



135; Primates, 138; Bra- 



dypodidre, 141 ; Pipa, 



141; Rana, 142 



dimorphism in respect of, 



138 ; distribution to 



limbs, 143 ; Homeeosis, 



144; recapitulation, 144 



Spinal nerves, principles of distribution, 



143 

 Spiracle, extra in tadpole of Pelobate*, 



465 

 Stability, Organic, 36 

 Starfishes, theory of origin of repetition 

 in, 29; variations in number of rays, 

 439 ; multiplication by fission, 433 

 Stentor, duplicity, 566 

 Sticlioj)us, arrangement of tube-feet 



changes with age, 435 

 Stickleback, variation in number of 



bony plates, 276 

 Stomobrachium octocostatum, variety 

 having tentacles in double series, 

 425 

 S trau galia, double (?) antenna, atra, 



551, calcarata, 551 

 Strategns antceus, extra legs, 512 

 Struthio, brachial plexus, 130 

 Styela, variations in branchial sac, 172 

 Subemarg inula, extra eye, 279 

 Substantive Variation, distinguished 

 from Meristic, 23; cor- 

 related with Meristic in 

 vertebra?, 125 

 in size, 38, 40; in colour, 

 43 — 48; in colour-pat- 

 terns, 48 — 54 ; miscel- 

 laneous, 54 — 60 

 Swan, cervical vertebrae, 33; colour- 

 variation of young, 44 ; brachial 

 plexus, 130 

 Symmelian "monster," 459 

 Symmetry, the conception of, 19, 569 



a relation between optic- 

 al images, 19 

 almost universal pre- 

 sence of in living or- 

 ganisms, 21 

 of mammae, 191 

 in dental Variation, 267 

 in digital Variation, Man, 

 324,402; Cat, 314; in 

 manus and pes, 4U3 

 in nuclear division, 430; 

 in variations in seg- 

 mentation of ovum, 

 463 

 in variations of homo- 

 logous twins, 559, 560 

 in double monstrosity, 



559 

 Bilateral, characters of, 

 88; as appearing in 

 variations of flat- 

 fishes, 467 

 Major and Minor, 21, 86 

 Primary and Secondary, 



90 

 Kadial, characters of, 89 



