IOC, MKUISTJC VARIATION. [PARTI. 



cartilage "i- by two cartilages. The cartilage of the left 7th rib is 

 als.. double I'm- 1^ inch, all the others are normal. 2. LI -ft fourth 

 rili becoming very broad and bifurcating in front; two large spaces, 

 on.- in t IK- b.iiie, one at the bifurcation, o. Left fourth rib becoming 

 broad t.i \\ards sternal end, where it joins bifurcated cartilage. In 

 til- three cases the division affected the 4th rib. Three others 

 an in \\hich the rib affected was probably the 4th or oth. 



Si 1:1 i HI. its. .}. ,./<ir. A nut. Plii/s., Ser. 2, Vlll. IS?."), p. 51. Such 

 cases are oft.-n recorded and preparations illustrating them may 

 ! ii in most nni-eiiins. 



I -idt - these cases of obviously M-ri-tic Variation, there are 

 maiiN \\hidi are r.uiibined with Homoeosis so as to produce far 

 anatomical divergence. Though in some of these examples 

 tin-re ma\ be change in the total number of vertebra- shewing 

 thai true Meristic change has occurred, they cannot well be treated 

 apart hm tin- m-. re di-tinctly Homoeotic cases. 



I b -MI I:-- 1 1' \'.\I:IA i MX IN VERTEHK/E AND RIBS. 



in vertebra may be best studied in Mammals, 



, 



an.! tin- following account in the tir-t instance relates chiefly to 

 them. r.etoie considering the details of such \ariations in vertebra- 1 , 



it may be useful to d, -senlie briefly the ordinary system of oe- 



dat'lle \\hich is here followed. I 1 1 ! 1'ea I i I Ig t ll JS M ll ij ect it IS 1111- 



-ible to employ a terminology \\hich docs not seem to imply 

 ptance of the \ie\\ that 1 1 1 e iv is a true homology between the 

 individual \eiiel, ra of t\\o >pin.-> containing different total num- 

 ber- for all the nomenclature of Comparative Anatomy is devised 

 on thi> hypothesis. This ditHculty is especially felt in regard to 

 vertebrae, and at this point 11 should l,e expressly stated that ill 

 using the ordinary terms M o Midi assent is intended. This matter 

 has already bee,, lefenvd to m Section \'l. of the Introduction, 

 and will lie dis, 'iis.,., | in relation to the facts to be given. 



.1 .ilmim ' is ili\i.ir.l into \\\,- regions: r,i\i,al. di.rsal. lumbar, 



i .111 ! iiliMilnt. 1\ cl.-tini il. luit tho folli>\viii._' 



ilifin. 

 i tli.' ant. ..... ]>'.rtimi of tin- i-.ilumn, which either 



ii.s wliii-li .to in. i K arli tli,. Mi'i-mmi. I>,ir*<il 

 whi.'h li.- |n.-i.-i:.,r l., th,- i-,-i-vi<-als ami ha\c moveable rilis. 



I.i"">"ir . ihi,-..- uhi.-li L to the dorsals and ha^ ..... moveable ribs! 



:inn..i 1..- .I. tiiii-.i in t.-i-Mi> u|i|,ii,-ai..i- even to tin- whole class ol 

 ii"H""ii'- - 'iiMil.'iaii.ni. it \\ill ! cnouph to use the 



i'-"ii in th" rilj given to it in human anatomy, to mean those vertebra 



wJn.-i, an- Hiik\,- i ether t.. fmni a .-a. -mm. Caudal vertebrtB are vert.-lira- 

 .111. 



The characters thus defined an- distributed among the several 



vcit.-bra- acc,,rilin- to their ordinal positions Among mammals 



th.- number of vertebra \\hi.-h develop the characters of each re- 



i., \\ . 11.. .V,im/,M/.<. I.ii-iii : i ,iwl Kstnic!. IS'.ll, j>. 41. 



