florida, metaxytherium floridanum.

DESCRIPTION OF A NEW FOSSIL SEA COW FROM

FLORIDA, METAXYTHERIUM FLORIDANUM.

By

OliverP.Hat.

Associate of theCarnegieInsiitution ofV,\is}iii}{/i(nt.

IntheUnitedStatesNational

Museum

isapart oftheupperright maxillaof a sirenianwhichisof greatinterest. Itwasreceivedalong with other specimensby Mr. GeorgeC. Matson,oftheUnitedStates Geological Survey, in 1911, and is recorded as having been found

1 mile west of Mulberry, Florida, in pit No. 7 of the Prairie Pebble Phosphate Co. Matson figured this bone^{^} under the

name

"manatee." Inthecatalogue of theUnitedStatesNational

Museum

thespecimen has receivedthe

number

7221.

The

fragmentpresents the hinder part ofthe rightmaxillary (pi. 1, figs. 1-3), extending from its articulation withthe palatineforward to the front ofthe sockets forthe anteriormolar present. Nearthe front end,on the outerside of the bone, is a break which represents the base of the processwhichpassedoutwardtojointhemalarbone.

The

maxilla is solidand heavy andhassufferedlittleerosion.

The

fragmentcontains thehindermost molartoothandthe sockets,mostlyfilledbythe roots, of threeother molars.

An

examination ofthespecimen showsthatit isclosely related to the specieswhich havebeen arranged underthe genusMetaxytherium.

The

fragmentofthemaxilla (pi.1, figs.1-3) hasa totallengthof106

mm. The

widthat themiddleofthe penulti- mate molaris40

mm.

^;theheightatthesameplace,39

mm. The

whole base ofthemalarprocessispresentandithad afore-and-aft extent of about 44

mm.

^Itsthicknesswasgreatestbehindand amountedto about 18

mm. Toward

thefront theprocess thinned out to asharp edge.

As

alreadystated,therewereoriginallypresent fourmolars (pi. 1, fig. 3).

The

hindermostoneis almost entireand isbut little worn.

Of

the two immediately in front of it there are present only the roots; of the next one,only the sockets; and of the sockets of this

>Bull.No.604, U.S.Geol. Surv.,pi.12,figs.A,B.

No.2438-ProceedingsU.S.NationalMuseum, Vol.61,Art. 17.

1

Z PROCEEDINGS OF

THE NATIONAL MUSEUM,

vol. 61.

molaronlyapartof the outerfrontoneispresent,thebonein front of it being gone.

The

total length of the tooth line was ^close to 85

mm. The

first molar appears to have had its transverse axis turned so as to

make

an angle of about 45° with the tooth line, the inner end being turned backward so that the inner root is op- positethe front andouterroot ofthesecond molar.

From

the outer border of the outer and hinder socket to the inner border of the inner socketisa distance of 22

mm. The

rootsofthe secondmolar are present in their sockets. Evidently this tooth and the succeed- ing onewerein the jaw

when

it was exhumed. This second molar hasthree roots, as the othermolars, two outer ones and one inner.

The

distance acrossits outersocketsis 19mm.,that acrossthe outer sockets of the third molar is22

mm.

; and this seems to havebeen the length of the crown of this tooth.

The

tooth appears to have had a width of about 25

mm. The

roots of the hinder molar are large.

The

outer anterioriswholly hidden.

The

outer hinder root sentitsextremitythroughthebone ata distanceof 31

mm.

fromits

base (pi.1, fig.2).

The

innerrootisexposed nearlyitswholelength on the inner face of the bone (pi. 1, lig. 1). It has a length of 40

mm.

andadiameterofabout13

mm.

^atitsbase.

The

crownof thehinder molarhas losta little ofitsenamel in a fewplaces; but the loss has notseriously injured it. Its length is 26.5

mm.;

its width, 25

mm.

^Ithadonlyjust begunto sufferwear.

It presents essentially the characters of thegenus Metaxytherium, as these havebeen expressed by Abel.- Figure 4of plate 1 repre- sentsthetooth withthe conesrestored so as to showtheir positions.

The

enamel of the tooth is strongely wrinkled.

Running

across thetoothaboutthemiddleofthelengthisa deepvalley. Itscourse

is not ^direct, but from the outer side it runs slightly forward in front of the metaconule and then swerves slightl}- backward as it passes to theinnersideofthe tooth.

The

valleyismostwidelyopen near ^its outerend,butit isnarrowed at itsimmediateentrance by a littleaccessory conule attached to the base ofthe metacone.

On

theotherhand, thereare noaccessoryconulestoblockup theinner endof the valley, such as Abel has represented^{in his} figure 17on his page 149.

The

protocone, the protoconule, and the para cone stand in a straight transverse row.

The

paracone and the proto- conuleareveryclose to eachother.

The

former issomewhatlarger than the latter.

The summit

of the protocone is

worn

dov\"n and theprobable shallow notch between it and theprotoconule has been effaced. There is a large anterior talon; and, on the outer half of thecrown, thisisseparated fromthe paracone andthe protoconule byawide and deep valley.

The

outer half of the talon is narrow

»Abel,Abb.Geol. Rcicbsanst.,Wien,vol.19,Heft.2,pp. 148-151.

ART.17. A

NEW

FOSSIL SEA

COW FROM

FLOEIDA

—

^{HAY. 6}

and sharp, butit widens toward the lingual side of the tooth and becomes broadly confluent with the protocone. If there

was

^origi-

nally a valley between the talon and the protocone, it has disap- pearedthrough^wear.

The

metaconule occupies a central position in the tooth, behind the transverse valley. It is closely connected with ^the hypocone, apparently lessclosely with the metacone. ^Itexceeds the latter in size. In31.krahulefzi,accordingtoAbel'sfigure,itissmaller than the metacone.

The

hypocone is large.

At

the rear of the tooth, closing the gap between the hypocone and the metacone, are two accessory conules, and there is another behind and outside of the hypocone.

Bounded

by these behind and by the hypocone, meta- conule,andthemetacone infront and at thesides, isa considerable pit. IntheEuropean species of

Metaxythermm

^justmentioned this isfilledwithsmall accessorytubercles.

The

baseof thetooth seems to be covered with a considerable coat of cement and this spreads

upward

in athinlayeronthecrown, especially inthevalleys.

This tooth differs from the teeth of all the species of Metaxy-

thermm

figuredby Abelinbeing broaderinproportiontoitslength.

Nothingis

known

about theabundance ofthis species. In collec- tions

made

from the phosphate deposits about Charleston, South Carolina, portions of the slmllsand limb bones of sirenians are not rare.

They

appeartobelongtomore thanonespecies andprobably to

more

than one genus. ^It is, however, at present impossible to correlateanyskullbones or limb bones with thejawabovedescribed.

It is impossibleto determine with accuracy the ^geological age of this species. It belonged probablyeither to the

Upper

Miocene or tothe

Lower

Pliocene.

The

Europeanspeciesbelongto theMiocene orinparttothe Oligocene. AccordingtoSellards^{^}the pebble phos- phate bedsatMulberryreston phosphatic marlsofsupposed

Upper

Oligocene age, and havebeen derived from the latterby reworking and concentration.

The

fossilhere described is therefore probably residualfromtheparent formation, the

Upper

Oligocene.

From

Mr. Charles T. Earle, there has been^lately receiveda con- siderable lot of fossil bones and teeth which

had

been washed up on the beach at

Palma

Sola, Manatee County, Florida.

Among

theseremainsare teeth and bones ofhorses, camels,bisons,Elephas cohimhi, etc. These belong certainly to the Pleistocene, Other bones andteeth are present, which appear to belong to Miocene or Pliocene deposits. Such are teeth of Carcharodon megaJodon, ^C.

aurlcidaius., Hemipristis ^{serra^ Lartina} cuspidata, a part of the beakof aplatanisted porpoise,anda tooth ofa seacow. There are

»Fla. Geol. Surv.,vol. 7, pp.52-84.

4

PROCEEDINGS OF

THE NATIONAL MUSEUM.

vol. CI,

besidessomebonesofland tortoisesandapart of ametapodial of a camel;butthese

may

belongtothe Pleistocene.

The

sirenian tooth is of such a size and structure that it

may

wellhavebelonged tothe speciesofanimal thatpossessedtheupper jaw andteeth aboA^e

named

Metaxytheriumfloridanum. This tooth

is apparentlya lower right third molar,and it is well

worn

(pi. 1, fig. 5).

The

length is 25.5

mm. The

width in front is 20

mm.

There are present two well-preserved roots.

The

anterior occupies thewidthof thecrownin front.

On

theoutersidethe cleftbetween

itandthe hinder rootis

somewhat

behindthemiddleofthe length

;

on the inner side, considerably farther in front.

The

hinder root

is compressed from side to side. Unfortunately the enamel is

much

broken

away

from ^{the outer} face of the tooth and

somewhat

less from the inner face.

At

the front of the tooth there appears to havebeen a deep valley, which extended backward between the protoconid and the other elements of the front crest. This valley has been

worn

quite toitsbottom. Evidentlyitlimited posteriorly the strongly developed anterior cingulum.

There appearsto havebeen an accessory cusp ^at the base of the metaconid, onits buccal side.

The

valley which separates the two principal crestsisseento extend half

way

acrossthe toothfrom the innerside.

On

account of theheavy wear there are not seen any remains of accessory cuspswherethetransverse valley openedout on the outer face of the tooth.

For

the same reason the exactstructure of the hinder taloncan not be determined by the writer; but this talon is welldevelopedandthereweretwoorthreeaccessoryconules.

This toothisprovisionally^referred tothe species

M

etaxythermm floridanum.

EXPLANATION OF

PLATE.

Metaxytheriumfloridanum,newspecies.

Figs.^1-3.Partof right side ofupperjaw. X3/4. Type.

1. Viewoflingualface.

2. Viewofbuccalface.

3. Viewof alveolar faceshowing hindermost molar and the roots and soclietsofthreeotherteeth.

4. Hindermost molar restored. XI. c^, anterior cingulum; ^c", c^, three conules belonging to hinder cingulum; hy, hypocone; mo, metacone;tul,metaconule; pa,paracone; pi,protoconulus;pr.pro- tocone.

5. Lowerrighthindermost molar of a referredspecimen.

XL

U. S. NATIONAL MUSEUM