Abnormalities in the Ribs of Birds

iSSS.] Gc/icral Notes.

32O

theskeletonofabirdisan iiitciostiiig fact,anditsees its counterpait in therudimentarylimbsinsucha lizard asOphisaurusventralia.

While engaged upondissecting the eyes of adultRavens{Corviiscorax siniiaius),Ihave always foundafirmosseousplate,ofanellipticaloutline, withamajoraxisof

some

5or 6 millimetres surrounding theentranceof the optic nerve,on the outer coat of the eye. In a 'Bulletin' which I

haveinthehandsof theSmithsonian Institutionfor publication,Ifigure thisstructure, as well as the rudimentary metatarsal bone,towhichI

havealhuicilabove.

—

R.

W. Shufeldt,

Fori Wing-ate,

New

Mexico.

Abnormalitiesinthe Ribs ofBirds.

— Those who

have examined

many

series of skeletons are well aware that the nuiiiber ofribs inanygiven speciesisliable tovary,andthatananimal

may

possessapair morethan thenormal

number

forthespecies,or thatinexceptional casesapair

may

be wanting.

The

additional pair ofribsusuallyappearson thefirst lumbarvetebra, orwhat would normallybe thefirst,although

now

amithenashort, st\li- form pairofpleurapophyses inay bepresent t)n the seventh vetebra of

mammals,

orin fishesonthee\-occi])itals.

The

greater

number

ofsegmentsinthe vertebialCf)liniin,andthe

more

generalizetl(lieanimal, the greaterseems the tendencyto variation,and intheUrodeleBatrachiaeventhe

number

of dorsal vertel)r;eisextremely inconstant.

The

following list ofcostalabnormalities, noted in a Cf)mparati\elv small

number

of skeletons,would seem toshowthat inbirds therib ele-

ment

issubjecttofrequentvariations.

Galeoscoptcscaroli/wnaiswithbuttivepairsofcompleteribs,insteadof thenormalpasserine

number

ofsix,theabnormality beingcaused In the lack ofaha-mapophysisontheribattachedtothefifteenthvertebra. 'I'he styliformrilionthefourteenth vertebrawasalsoreducedinsize.

Galeoscop/escaroliiiri/siswithsevenpairsofribs, ahiemapophysiscon- necting the ordinarilyfreerib of the fourteenth vertebra with the ster-

num.

Mclaiioptilaglahrirostris.andClixneola riparia,each withaseventh pair ofribswith attachediKemapophyses onthesecondvertebraof the 'sacrum.'

^uiscaliispurpuniis andSturi/e/Za iiitiona i/eglecta,eachAvithanaddi- tionalpairof short slenderribs,devoid oih;emapophyses, onthesecond vertebraof the 'sacrum.' This isarathercurious coincidence,asthetwo birdsare presumablynearlyrelated. It isthe

more

interestingfromthe factthat

among

birds the dorsal portion of therib is thefirstto be sup- pressed,andinstances are numerous

—

^as

among

Raptores

—

wherea pair ofhremapophysesisnormallypresentwithout theslightest traceof corres- ponding pleurapophyses.

An

intermediate condition is found in

some

birds,«.^., Trochilus colubrisand Cypselus apus

—

a complete haimapo- physis supportinga pleurapophysis

whose

upper moietyislacking.

Examinationof the largeseriesof sacraofAlca imfennisinthecollec- tionof theU.S.National

Museum

showsthat in this birdanextra(ninth)

7

70

Correspondence. [J"ly

pairofribswasnotiiitVequentl vpresentonthesecond'sacral'vertebra.

At some

futuredayIhopetoascertaininwhatpercentage ofGreat

Auks

this condition prevailed, but themostinterestingfactisthat

when

theadditional pair ofribs is present there is usuallyatthe

same

timea small para- pophysis developed onthefirsttrue sacral vertebra,as ifthe rib-creating forcehad beenfelt stillfurther

down

thelineofvertebra;.

Theseabnormalitieshave been mentioned,astheyseemto haveabear- ing onthe reductioninthe

number

of vertebrse whichBaur, Balfourand Parkerhave

shown

has taken place

among

birds,andthey

may

probably be regardedasthereappearancesofribsonce normallypresentinthean- cestraltypesof existingbirds.

—

Frederic

A. Lucas, Washingion, D. C.

CORRESPONDENCE.

[Correspondents arerequestedtoivritebriefly and to the poiiil. Noattention -.vill bepaidto anonymouscommunications.^

The Sternum

in the Solitary Sandpiper,andother Notes.

To THE Editors

of

the Auk

^:

—

Dear

Sirs:

Some

^littletimeago,whilelooking over several skeletons of the SolitarySandpiper{Totattiissolitariusof theA. O.

U

checklist),

whichI havein

my

private collection,Inoticed that thesternum ofthis birdhas butasingle largenotchoneitherside.

Now

the only twoother alliedspeciesinouravifauna, sofaras is

known

to

me

atpresent,thus constituted, are the

Woodcock

and Wilson's Snipe{Gallijiag-odelicata)

,

and I

am

uncertainaboutthegenus Macrorhafiipliiis, as I have not, as yet,lookedupthepointin the species therein contained. Possibly, too.

Tetanus ochropus

may

possessasternum with butapairofnotchesinit,

andifthatbe thecase,I

am

of theopinionthatthecharacterisverylikely tobe associatedwithother distinguishing pointsinthe

economy

of these two birds,ofample importance,I think,to guarantee us in restoring for their reception, the genus Rkyacophilus., which change I propose in the present connection. Such forms as Tetanus fiavipes and T.

melanoleucushavethe usual ybwr-wo/c/^Cf/sternum, as isthegeneralrule

among

Limicoline birds.

To

furnish certain comparative notes onthis point,

we

find that Sir Richard

Owen,

inspeaking of thesternumas itisfound incertain birdsofthisorder,says, inthesecondvolumeof his'Comparative Anat-

omy

and Physiologyof Vertebrates,' on page 26, that " the

woodcock

(^Scolopax)has a pair of notches,with the outerboundaryslender, and shorterthanthebroadintermediatetract,thegambets {Tetanus^,avocets,