592 



IXDEX OF SUBJECTS. 



Tritmophonu, segmentation of, 



YV/yir< rlitritjera, rhinophore tritid. 2*n 

 Triton, li-^'s repeated, '>'>'> 

 Tn>!iltiilijt<'*, ve.rtelii.-e. 116; teeth, 202 

 'J'rtijiitliiHotii.-i, vertebra-, 128; scales, 270 

 Trout, bulldog-headed, 58, 59; axial du- 



Tulip, Meristic Variation in, 00 

 Turliot, pigmentation oflower side, 407, 



170 



'J'ltnluK, brachial plexus, 131 

 Turkey, dibits, 393 



Twins, homologous, 559; Simultaneous 

 Variation of. as a case of Bi- 

 lateral Symmetry, 559 

 Siamese, peculiarities of, 500 ; 

 thoracopagous, 560 

 in Kchinod.-rms and in Aniphi- 



oxus, 35 

 Typosyllis, double head, 504 



I'l-n itim. extra parts in chela, 530 



Ulna, a second, 331 



Ulnar nerve, variations in composition 

 of, 13(5 ; a second. 333 



Ungolata, teeth, 243; digits, 360- 3'.<>.397 



I' n ion. median, 458; of horns of Roe- 

 buck, 4GO; of eyes of Bee, 461; of 

 kidneys, 45!); of tentacles of Limit. r, 

 400; of tentacles of Helix, 401; of 

 posterior limbs of Vertebrates, 459; of 

 dibits in Ox, 383, 386; of digits in 

 Pig, 387390 



Units, of Repetition. 550 



I'mi'tnx, braehial plexus, 131 



Ureters, supernumerary, 27* 



I'seless" parts, supposed variability of, 

 78 



Uterus, double, Darwin's comment on, 

 77 ; is a case of median division, 451 



Utility, fallacies of reasoning from, 12 



Uvula, division of, 451 



nt n lii n tn, colour- variation, 46 

 nrtic(C, extra wing, 2*3 

 /. eye-spots, 299, 300 

 Variation, denned, 3 



the Study of, as a method 



of attacking the problem of 



Species, 6 

 Continuous and Discontinu- 



ous, 15 

 Meristic and Substantive, 



distinguished, 23, 24 

 magnitude of integral steps 



affected by Merism, 25 

 about a Mean form, 37 

 perfection in, 00, 01 

 causes of, 78 

 Homo otic, s5. iii \rrtrlme. 



100; in Arthropoda, 146; 



in teeth, 272 

 Simultaneity of. in repeated 



parts. 308, 102, 125, 401 



Variations, minimal, questionable uti- 



lity of, 10 



Vertebra? , Meristic Variation in, 102 

 imperfect division, 103, l'>^ 

 Homieotic Variation, 106 

 reduction in numbers, Man, 



111 



numerical variation, 102 

 Man, 103, 100110; Anthro- 

 poid Apes, 116; Bradypodi- 

 dffi, llH; Carnivora, 122; 

 Reptilia, 123 ; Batrachia, 

 124 ; features of Variation 

 recapitulated, 127; correla- 

 tion with spinal nerves, 113, 

 115, 139, 145 



l'r.*}n-rii* luriilii*. extra eye, 280 

 Veronica lni.rhnumii, numerous symme- 

 trical variations in, 70; illus- 

 trating variations of Bila- 

 teral Si-ii.-s. 41* 

 Viverridffl, teeth, 227231 



Waigiu, female Phulanger 



coloured like male in island 

 of, 254 

 Wall butterfly, variation in ocelli and 



neuratiou, 300 



Water-pore, extra, in Jlijiiiuiiirin, 460 

 Webs, between toes of Duck, absent, 401 

 Weevils, four visible joints in tarsus, 25 

 Wing, supposed to replace a leg in Z//- 



rjitna, 148 



Wings, supernumerary in Insects, 281 

 fore and hind, varying simul- 

 taneously in Lepidoptera, 2'.i3 

 quills of, varying with quills of 



tail in Pigeons, 309 

 Woodpecker, Green, colour-variation, 43 



Xmitho 2>unctulutnx, duplicity of index, 



542 

 Xiphopagous twins, transposition of 



viscera in, 560 

 Xylntrupc.i ,ji,l,nn, variation of horns in. 



38 



Yellow, variations of, 43-48, 73 

 Yew, yellow-berried, 47 



* culij'orniftnux, molars, 243 

 Itilmtii.*, premolars. 23*. 212; 



molars, 243 



Zebra, repetition of stripes in, 20 

 /.i'iiiii>l>tern*, white varieties, 407; varia- 



tion in dorsal fin, 471 

 Zaiinliri.-i quadripunctata, double (?) an- 



tenna, 551 



/in/it,'^ ]>r<i n.f/ii. extra antenna 3 , 522 

 '/. ijih' mi tili]H'it<liil", colour variation, 46 

 supernumerary wing, 



148 



mi nog, colours, 46; extra wing, 

 2*4 



